Sec. 17. (a) A majority of the members of the board constitutes a quorum for the transaction of business. The affirmative vote of a majority of the board is necessary for an action to be taken by the board.
(b) A member may vote by written proxy delivered in advance to the chair or secretary of the board.
(c) A vacancy in the membership of the board does not impair the right of a quorum to exercise all rights and perform all duties of the board.