provided, however, that where one or more vacancies exist on the board and the board is not otherwise prohibited from entertaining a motion requiring such a supermajority, such motion shall carry on the affirmative vote of two-thirds of the members present. On any motion requiring a supermajority for passage, any abstention not authorized as provided in this chapter shall be deemed an affirmative vote for purposes of passage or failure of such motion.
OCGA § 50-32-13