Laurence, J.
This appeal presents us with an affecting legal struggle between devoted parents and conscientious public officials over the most suitable care for a severely disabled and retarded young woman. It arises out of a complaint for declaratory and injunctive relief filed in July, 2005, by Frank A. and Kim A. (collectively, parents) against the Commissioner of the Department of Mental Retardation (DMR), seeking to prevent the DMR from transferring their then twenty-two year old daughter, Molly, from her long-time residential placement at Crotched Mountain Rehabilitation Center (Crotched Mountain) in New Hampshire to another facility in Massachusetts that the DMR deemed appropriate and less costly, a transfer that the parents maintain would offer Molly inadequate care and would violate the DMR’s statutory, regulatory, and constitutional obligations to her. A Superior Court judge allowed the DMR’s motion for summary judgment and dismissed all three counts of the parents’ complaint.3 We now affirm that judgment as to counts I and HI and reverse as to count H.4
1. Background. From the materials submitted to the judge in conjunction with the parties’ summary judgment motions, the material facts relevant to the disposition of this appeal are as follows.5 Molly, born on March 2, 1983, suffers from Rett’s Syndrome (Rett’s), a progressively debilitating disorder akin to [269]*269autism that afflicts only females and is often associated (as it is in Molly’s case) with enfeebling symptoms, including profound mental retardation (Molly has the cognitive function of a twelve month old child), legal blindness, impaired hearing, inability to speak, constant hand-wringing, and seizures. Molly cannot feed herself or attend to any of her personal or hygienic needs unassisted. Unlike many Rett’s patients, she can walk independently, although haltingly.
Since 1994, Molly has resided in a skilled nursing unit at Crotched Mountain in Greenfield, New Hampshire, where she has remained to this day. Crotched Mountain is a private residential facility providing a wide array of rehabilitative services for persons who are mentally retarded, vision and hearing impaired, and otherwise seriously disabled. Molly has received physical, speech, occupational, and music therapies, and (most relevant to the instant case) has had a “one-on-one” aide assigned to her at all times. As a legal resident of Bedford, Massachusetts (where she lived with her mother, Kim A.),6 Molly has been provided special educational services through the Bed-ford school district and the Massachusetts Department of Education, which placed her at Crotched Mountain and were responsible for funding her stay and services there through her twenty-second birthday, pursuant to G. L. c. 71B, usually called “Chapter 766” (of the Acts of 1972). Under G. L. c. 71B, §§ 3 and 5, those eligible for special education services receive funding for such services through the public school system of their legal residence until they graduate from high school or turn twenty-two years old. Under G. L. c. 7IB, §§ 12A-12C (turning twenty-two [270]*270statute), upon turning twenty-two (as Molly did on March 2, 2005), the recipient “ages out” of the public school system and becomes eligible for adult services funded by the DMR.
A year before Molly’s twenty-second birthday, a DMR transition coordinator, Barton Price, became involved with Molly and her parents to plan and facilitate the transfer of responsibility for her services from the Bedford school system to the DMR. The parents hoped that the DMR would permit Molly to remain at Crotched Mountain, where she had made unusual progress for a woman her age afflicted with Rett’s.7 Although the DMR briefly considered Crotched Mountain as an appropriate facility to provide adult services to Molly, for a number of reasons it soon began focusing on alternative placements within the Commonwealth.8 On October 5, 2004, it sent to the parents at Molly’s Bedford address (where it mistakenly thought the parents resided together) an “individual transitional plan” (ITP) for Molly, as required by the turning twenty-two statute, G. L. c. 7IB, § 12C. The bulk of the ITP, which was drafted by Price, described Molly’s ailments (including the fact that she “continues to have periodic seizures”) and needs. It concluded with an unelaborated observation that Molly “will be unable to remain at [Crotched Mountain] beyond her 22nd birthday on March 2, 2005”; the clear implication that she would then be transferred to an appropriate residential placement in Massachusetts yet to be determined; and the alarming (to the parents) statement that, if no suitable placement was found for Molly by that time, she would be sent to the Bedford residence with unspecified DMR “support.”9 The ITP included instructions on how to file an administrative appeal should the parents “reject” the plan.
[271]*271Dissatisfied with the ITP, on November 19, 2004, the parents filed a timely appeal to the bureau of transitional planning of the Executive Office of Health and Human Services (EOHHS), pursuant to 101 Code Mass. Regs. § 10.03 (1999).10 About one month later, they received a letter from the EOHHS acknowledging receipt of the appeal, but never received a response to their appeal in the form of a written ruling affirming or modifying the ITP, as required by the regulation. During this period and into early 2005, the DMR did, however, continue to work with the parents regarding Molly’s placement in an appropriate adult facility. On February 23, 2005, after a number of meetings among the DMR representatives, the parents, and the staff at Crotched Mountain,11 Mary Beth Coyne, the DMR’s area direc[272]*272tor for central Middlesex County, informed the parents that the DMR would not fund Molly’s continued stay at Crotched Mountain past her twenty-second birthday.12
During February and March, 2005, the parents visited or considered several Massachusetts facilities suggested by the DMR as appropriate residential placements, but found each one unsatisfactory, primarily because they would or could not provide the constant one-on-one care and twenty-four hour nursing services the parents believed were essential to Molly’s welfare and safety. March 2, 2005, Molly’s twenty-second birthday, came and went without resolution of the issue. On March 24, 2005, the DMR sent a “revised” ITP to the parents that added to the list of Molly’s medical problems but left the statement of her needs unchanged. It reiterated that Molly would not be able to stay at Crotched Mountain beyond her twenty-second birthday (although she already had for three weeks, at the DMR’s expense) and that she would be sent home with DMR “support . . . until an appropriate residential placement can be developed.”
The parents continued to believe that the ITP, even as revised, was incomplete and did not comply with the DMR regulations. On June 3, 2005 (within the ninety-day administrative appeal period), the parents rejected the revised ITP and again appealed, once more stressing the necessity for twenty-four hour per day, one-on-one care because of Molly’s seizure disorder and drop attacks, which “have increased in number and length over the past year.” On the record provided this court, no response appears ever to have been made to the parents’ second ITP appeal, and no further proceedings thereon occurred.
Subsequent to the DMR’s issuance of the revised ITP, in late March, 2005, the DMR sent two representatives, Dr. Allen [273]*273C. Crocker and Sharon Oxx, a registered nurse, to Crotched Mountain to review Molly’s care plan and determine if her needs could be served in a community setting with less intensive care than the parents were demanding.13 They observed Molly “in a number of settings” for an undisclosed period of time and met for approximately two hours with senior Crotched Mountain staff who supervised or cared for Molly. Based on his visit, Dr. Crocker concluded that Molly’s “seizures ... are evidently mild, infrequent and not disabling” and the issue of falls “also do[es] not appear to be important,” so that Molly could do well in a small group home with a two-to-one patient-staff ratio and intermittent nursing visits. He also noted that in his experience, the overwhelming majority (eighty per cent) of Rett’s patients, in fact, live at home with their families.
Oxx opined that Molly was “not as medically fragile” as the parents maintained; that her seizure disorder was infrequent and “appears to be fairly well regulated”; that over the prior twelve months, no reported incidents of injuries associated with seizures had been reported; that Molly did not need twenty-four hour nursing care or constant one-on-one staffing; and that her needs were in fact similar to those of the great majority of people the DMR served (in that she had no self-preservation skills, minimal daily living activities skills, and limited abilities to communicate) who thrived in community residential care programs, as could Molly.
Recognizing the likelihood of impasse and litigation, in the early spring of 2005, the parents retained counsel to represent them in their dealings with the DMR. Through the spring and early summer, counsel communicated to the DMR at greater length the parents’ reasons for rejecting the suggested Massachusetts placements and elaborated on the parents’ concerns [274]*274for Molly’s future care, but no agreements could be reached. On July 1, 2005, the DMR sent the parents’ counsel a letter recapitulating the several alternative placements the DMR had suggested, mentioning several additional ones, requesting that the parents make a choice by July 8, 2005, so that the transition process could begin, and stating that the DMR would no longer fund Molly’s continued stay at Crotched Mountain after July 31, 2005.
Counsel’s response to the DMR, dated July 8, 2005, reiterated the parents’ objections to the facilities and services proposed by the DMR because none of them provided the level of services Molly’s health and safety required, most particularly “constant 1:1 staffing.” For the first time, the parents asserted that Molly, having turned twenty-two and been funded by the DMR since her birthday, was now entitled to invoke the provisions of G. L. c. 123B, §§ 1-3 (transfer statute),14 and lodged a formal request for an administrative transfer hearing and continued funding of Molly’s current Crotched Mountain placement. The parents’ counsel electronically mailed the DMR a second such request on July 12, 2005.
Receiving no official response from the DMR to either communication, and construing the DMR’s silence as reflecting a threat imminently to terminate Molly’s funding at Crotched Mountain and transfer her to an inadequate facility or home, the parents’ counsel filed the underlying complaint on July 22, 2005, seeking declaratory and injunctive relief15 on the basis of three arguments. In count I, the parents asserted that the DMR [275]*275was required to comply with the transfer statute, G. L. c. 123B, § 3, and prevail at an adjudicatory hearing before effecting a transfer of placement, because the DMR had already begun [276]*276funding Molly’s stay at Crotched Mountain subsequent to her twenty-second birthday. They argued in count II that the DMR had failed to comply with its obligations under the turning twenty-two statute, as set forth in G. L. c. 7IB, § 12C, and the Massachusetts Declaration of Rights, which mandate that the DMR provide Molly with proper habilitative services. In support of their position, the parents relied on experts16 who opined that Molly requires placement in a facility providing constant one-on-one care, chiefly because her seizures and falling risk pose a significant danger for her health and safety. The parents contended in count III that the DMR had also violated the procedural requirements established in the turning twenty-two statute and the DMR’s own regulations, 101 Code Mass. Regs. [277]*277§ 10.03, by providing them with an inadequate and noncompliant ITP and by failing to address and resolve their objections to the ITP.
2. Discussion, a. Standard of review. The parents contend that the Superior Court judge erred in denying their motion for summary judgment on count I and in allowing the DMR’s motion for summary judgment on all three counts. Much of the basic standard governing appellate review of summary judgments has been set forth in note 5, supra. As applicable to count I, the additional relevant principles are that (1) a summary judgment motion will be granted “if the pleadings, depositions, answers to interrogatories, and responses to requests for admission under Rule 36, together with the affidavits, if any, show that there is no genuine issue as to any material fact and that the moving party is entitled to a judgment as a matter of law,” Mass.R.Civ.P. 56(c), as amended, 436 Mass. 1404 (2002); and (2) “statutory interpretation is a question of law for the court to decide,” Annese Elec. Servs., Inc. v. Newton, 431 Mass. 763, 764 n.2 (2000), and can be appropriately resolved by summary judgment if there is no real dispute as to the salient facts, Community Natl. Bank v. Dawes, 369 Mass. 550, 553 (1976).
b. Count I. We agree with the judge’s observation that “[t]he issue at the heart of Count I is whether the Transfer Statute, G. L. c. 123B, § 3, applies to Molly’s situation ...[,] a question that [the parties agree] does not depend on [disputed] factual circumstances.” We further agree with the judge’s adoption of the DMR’s position that (1) the turning twenty-two statute is the primary process by which individuals receiving special education services under Chapter 766 are moved into the adult services system; (2) the transfer statute, construed, as it must be, in harmony with the turning twenty-two statute, did not yet apply to Molly’s situation because an individual service plan (ISP) had not yet been developed for her and such a plan is a precondition of eligibility for the transfer statute’s procedural protections17; and (3) the DMR was consequently not obligated, as the parents demanded, to prove in an administrative hearing [278]*278of the sort required pursuant to the transfer statute that Molly’s adult placement would meet her “best interest” — which, were the parents’ position correct, would require a placement giving Molly better services than those she was receiving at Crotched Mountain.18 The DMR’s view — with which the judge agreed — is that it properly proceeded under the turning twenty-two [279]*279statute, with its elaborate procedural structure for developing a transitional plan for an individual coming from special education into adult services,19 because the transfer statute only applies to individuals who have already completed the transition [280]*280to adult services and have been receiving services from the DMR under an ISP; and because (as explained in notes 18 and 19, supra), the DMR has up to twelve months following an individual’s twenty-second birthday to develop an ISP if an ITP has been developed for that individual.
Courts have long and consistently accorded “substantial deference to a reasonable interpretation of a statute by the administrative agency charged with its administration [and] enforcement.” Commerce Ins. Co. v. Commissioner of Ins., 447 Mass. 478, 481 (2006). See Amherst-Pelham Regional Sch. Comm. v. Department of Educ., 376 Mass. 480, 491-492 (1978) (upholding administrative interpretation of provisions of G. L. c. 71B). That deference requires, first, that we “apply all rational presumptions in favor of the validity of the administrative [construction of a regulatory statute] and not declare it void unless its provisions cannot by any reasonable construction be interpreted in harmony with the legislative mandate,” Consolidated Cigar Corp. v. Department of Pub. Health, 311 Mass. 844, 855 (1977). Even more decisively, it enjoins that, “[g]iven . . . two equally plausible readings of the statutory language, we [must] defer to the [agency’s] reasonable interpretation .... [0]ur role ... is constrained ... by the [reasonable] choice of the agency.” Falmouth v. Civil Serv. Commn., 447 Mass. 814, 821-822 (2006).
Accordingly, we must reject the parents’ proffered statutory interpretation, which is based on a literal reading in isolation of the provision of the transfer statute that requires an adjudicatory proceeding if the “guardian . . . for a mentally retarded person [281]*281who is receiving residential services through [the DMR]” objects to a proposed residential transfer of such person for whom an ISP has been developed. G. L. c. 123B, § 3, inserted by St. 1986, c. 599, § 39. The parents’ out-of-context reading contravenes the DMR’s reasonable position that the turning twenty-two statute initially governs the transition of all disabled persons, including those suffering mental retardation, into adult services via an ITP; and that the transfer statute itself presupposes that a post-ITP ISP will be in place before a mentally retarded individual becomes eligible for the transfer statute’s protections (see note 19, supra).20 Moreover, the parents fail coherently to counter the DMR’s plausible view of how the two statutes, which are clearly in pari materia, can be read “together [as courts must] to make ‘an harmonious whole consistent with the legislative purpose.’ ” Healey v. Commissioner of Pub. Welfare, 414 Mass. 18, 25 (1992), quoting from Registrar of Motor Vehicles v. Board of Appeal on Motor Vehicle Liab. Policies & Bonds, 382 Mass. 580, 585 (1981).
Further, the parents’ statutory analysis violates several other principles of statutory construction. We do not interpret regulatory statutes in a manner that imposes procedural requirements on an agency that are not clearly mandated by the statutory language. See Grocery Mfrs. of Am., Inc. v. Department of Pub. [282]*282Health, 379 Mass. 70, 79-80 (1979). Nor do we construe “statutes embodying procedural requirements” in such a way as to “create] snares for the unwary.” EMC Corp. v. Commissioner of Rev., 433 Mass. 568, 574 (2001), quoting from Becton, Dickinson & Co. v. State Tax Commn., 374 Mass. 230, 233 (1978). Additionally, the parents’ arguments neither address nor reflect the deference due the DMR’s expertise in interpreting and administering the statutes at issue, to which expertise courts afford “substantial deference.” Goldberg v. Board of Health of Granby, 444 Mass. 627, 633 (2005).21
More decisively, however, courts “will not adopt a literal construction of a statute if the consequences of such construction are absurd or unreasonable.” Champigny v. Commonwealth, 422 Mass. 249, 251 (1996), quoting from Attorney Gen. v. School Comm. of Essex, 387 Mass. 326, 336 (1982). We are bound to avoid an absurd or unreasonable result when statutory language is susceptible of a sensible, workable construction. Green v. Board of Appeal of Norwood, 358 Mass. 253, 258 (1970). The parents’ position, that the DMR is obliged to comply with the transfer statute once it voluntarily pays anything for an [283]*283individual’s services after her twenty-second birthday, would, if accepted, have three such undesirable consequences. First, it would yield the discordant result that the transition of mentally retarded special education recipients to the DMR would be effected through a different procedure than that applicable to all other special education students moving from child to adult services — a result inconsistent with the generality of the turning twenty-two statute as applicable to all disabled persons receiving special education under Chapter 766.
Second, it would have (as previously explained, see note 18, supra) the effect of requiring the DMR to prove that moving disabled mentally retarded individuals from their childhood special education facilities to adult placements would produce not merely continued services at the same level, but “improved” services. Such a financial consequence would conflict with the express limitation in G. L. c. 71B, § 12C, inserted by St. 1983, c. 688, § 1, that services provided to former Chapter 766 recipients are “subject to appropriation,” as well as with the conditioning of such services under an ISP to “the availability of resources,” 115 Code Mass. Regs. § 6.20(1) (2003).22
Finally, and perhaps most contrary to public policy, accepting the parents’ argument would undermine the cooperative approach to service delivery embodied in the statutes and the DMR regulations; would effectively penalize the DMR for its good faith decision not to uproot Molly precipitously, but rather continue to voluntarily fund Molly’s stay at Crotched Mountain beyond her twenty-second birthday while the parties attempted to negotiate their differences; and would most likely create a disincentive for the DMR to engage in future dispute resolution [284]*284negotiations with and temporary funding arrangements for any similarly situated guardians and their wards.
In sum, the judge correctly granted summary judgment for the DMR on count I of the parents’ complaint.
c. Count II. The judge was not, however, as sure footed in his handling of count D, which alleged that the DMR did not comply with its obligations under the turning twenty-two statute and the Massachusetts Declaration of Rights in that its proposed plan (the revised ITP) failed to provide Molly with the proper rehabilitative services to meet her needs —- most importantly (to the parents) Molly’s need for constant, twenty-four hour, one-on-one care to insure her physical safety because of her seizures and risk of falling. On this count, the judge concluded that the issue of the appropriate level and manner of services for Molly came down to a battle of experts,23 which could be resolved in the DMR’s favor by reason of its experts having opined that its decision to offer placements that would provide Molly with less intensive care than one-on-one was nonetheless a reasonable choice, because it was supported by evidence that the choice comported with accepted professional practice and standards.
The judge relied on a theoretically unimpeachable standard of appellate review — that when an agency has, in the discretionary exercise of its expertise, made a choice between two fairly conflicting but debatable views, and its choice reflects reasonable evidence (especially when supported by qualified experts), a court may not displace that choice or substitute its judgment for that of the agency. See Conservation Commn. of Falmouth v. Pacheco, 49 Mass. App. Ct. 737, 740 n.3 (2000), and cases cited. The judge’s reliance on that standard was, however, misplaced, because it applies to fully litigated proceedings where there have been sufficient agency findings, or equivalent factual bases, on which to exercise its statutory authority. In the summary judgment context, such reliance resulted in the disregard of the most axiomatic applicable principle: that summary judgment cannot be granted if the evidence properly before the motion judge24 reveals a genuine issue of disputed material fact.
[285]*285Viewing the facts in the light most favorable to the parents, we see as hotly disputed the most substantial issue separating the parties with respect to the DMR’s undisputed service obligation to Molly: namely, whether the placements proposed by the DMR would provide the habilitative services necessary to insure her physical well-being and safety so as to maximize her potential for self-sufficiency. See G. L. c. 71B, §§ 12A, 12C. We disagree with the judge’s observation that the rival experts’ opinions on that score differed only “in matters of degree” and merely reflected different “applications of professional judgment” and “differing assumptions.” There could not have been more pointed conflict between the parties’ experts with respect to the critical factual question underlying that basic issue — whether Molly required twenty-four hour, one-on-one supervision.
Doctor Crocker and nurses Shilo and Oxx opined for the DMR that Molly’s seizures were mild, infrequent, not disabling, and fairly well-regulated, and that the risk of her injury from falling during a seizure did not appear to be important, had [286]*286been overestimated, and was not a serious reality. Consequently, they saw no need for constant one-on-one care for her. The parents’ experts, Drs. Riviello, Wilson, and Daignault, on the other hand, described Molly’s seizure disorder as “intractable,” with her seizures increasing in number, progressively worsening, and creating a serious risk of injury from falls. Providing Molly with round-the-clock, one-on-one supervision was, they concluded, potentially a matter of life and death.
These opinions, which go to the very heart of the decision as to Molly’s most appropriate placement, are not mere differences in degree, but rather represent polar views regarding the outcome-determinative, unresolved issue dividing the parties. That issue manifestly requires trial. The judge (and certainly this court) may not usurp the function of the factfinder by passing on the relative credibility of the rival experts, evaluating the comparative weight of their evidence, assessing whether the DMR’s view of Molly’s condition is more valid or plausible than that of the parents, or concluding that the parents are unlikely to prevail on this issue at trial. See Attorney Gen. v. Bailey, 386 Mass. 367, 370 (1982). On this record, the allowance of summary judgment for the DMR on count II was error.
d. Count III. The parents alleged in count III of their complaint that the DMR’s revised ITP failed to comply with statutory requirements (particularly as to specifying the location and expected duration of services, G. L. c. 71B, § 12C); and that the DMR failed to comply with its own regulations by not modifying or affirming that ITP within thirty days following their appeal. 101 Code Mass. Regs. § 10.03. The effect of these procedural defects, they contend (based on their proposed reading of 115 Code Mass. Regs. §§ 6.20[4][b], 6.23[3], 6.23[5][a]), is that there was no valid ITP in existence on and after March 2, 2005, while Molly was receiving the DMR funding. The net result is that the transfer statute should have been applied to Molly’s situation, entitling her to an ISP within ninety days of her twenty-second birthday. Consequently, they argue, summary judgment on this count was inappropriate.
The parents devote less than two pages of their brief to this rather convoluted issue and rely on bare assertions regarding the meaning of the cited statutes and regulations, unaided by [287]*287precedential, or even analogous, supportive legal authority and contrary to Mass.R.A.P. 16(a)(4), as amended, 367 Mass. 921 (1975).25 Moreover, the revised ITP they attack — indeed, even the initial ITP — appears on its face to comply, if minimally, with the statute.26 Further, nowhere do they suggest how a timely DMR-developed ISP would have differed in any meaningful way from the DMR’s revised ITP — particularly in light of the express regulatory limitation on ISP-proposed services as being “subject to the availability of resources.” 115 Code Mass. Regs. § 6.20(1).27
The greatest difficulty with count III, however, is that, in substance, it presents the same pure question of law — did the DMR act as the law requires in proceeding in Molly’s case under the turning twenty-two statute rather than under the transfer statute — that the judge correctly resolved in the DMR’s favor in granting summary judgment on count I.28
[288]*2883. Disposition. The parents’ complaint specifically requested declaratory relief as to the applicability of the transfer statute to any DMR transfer of Molly from Crotched Mountain and as to Molly’s right to receive sufficient funding and services from the DMR for her continued safety and habilitation. The judge, however — perhaps in consequence of his “presumptions” that the Commonwealth “will honor its obligations” and that the DMR “will continue to work with Molly’s parents toward a placement that is optimally suited to Molly’s needs within the available program options and funding, and that satisfies accepted professional standards for meeting her developmental, medical, and personal safety needs” — simply dismissed the parents’ complaint after allowing the DMR’s motion for summary judgment. When a complaint requests declaratory relief, the judge must declare the rights of the parties, even when [289]*289relief is denied, Animal Legal Defense Fund, Inc. v. Fisheries & Wildlife Bd., 416 Mass. 635, 641 (1993), and even on motions for summary judgment, 146 Dundas Corp. v. Chemical Bank, 400 Mass. 588, 589 n.4 (1987).
Accordingly, the judgment is modified so as to declare that the provisions of the turning twenty-two statute, G. L. c. 7IB, §§ 12A-12C, and not the transfer statute, G. L. c. 123B, §§ 1-3, apply to Molly’s transfer by the DMR from Crotched Mountain to another placement for the provision of such services and supports as are in compliance with applicable statutory and regulatory criteria and requirements. In addition, for those reasons discussed supra, the judgment is affirmed in so far as it grants the DMR’s motion for summary judgment as to counts I and III of the complaint. The judgment is reversed in so far as it grants the DMR’s motion for summary judgment on count II, and the case is remanded for such further proceedings with respect to count II as are consistent with this opinion.
So ordered.