N.Y. Comp. Codes R. & Regs. tit. 8, § 279.5 – Answer.

(a) The respondent may, within five business days after the date of service of the request for review, answer the same, either by concurring in a statement of facts with petitioner or by service of an answer. Such answer shall conform to the requirements in section 279.8 of this Part.
(b) The petitioner may, within five business days after the date of service of a cross-appeal, answer the same, either by concurring in a statement of facts with petitioner or by service of an answer to the cross-appeal. Such answer shall conform to the requirements in section 279.8 of this Part.
(c) An answer, together with proof of service upon the petitioner, shall be filed with the Office of State Review of the State Education Department within two days after such service, together with the respondent's notice of intention to cross-appeal in the case of an answer with cross-appeal. No filing by facsimile or electronic mail shall be permitted.
(d) Additional papers in support of an answer.
A memorandum of law in support of an answer (or answer with cross-appeal), if any, must be served upon the other party to the hearing and filed with the Office of State Review together with the answer (or answer with cross-appeal). Such memorandum of law shall comply with the requirements of section 279.8 of this Part.
(e) Service.
Service of an answer or answer with cross-appeal may be made by personal delivery, United States mail, or overnight delivery service upon the opposing party or such party's attorney.