a. Unless otherwise provided in the certificate of incorporation, the bylaws, or this act, the members entitled to cast a majority of the votes at a meeting shall constitute a quorum at the meeting. The members present in person or by proxy at a duly organized meeting may continue to do business until adjournment, notwithstanding the withdrawal of enough members to leave less than a quorum. Less than a quorum may adjourn.
b. Whenever any class of members is entitled to vote separately on a specified item, the provisions of this section shall apply in determining the presence of a quorum of that class for the transaction of the specified item.