Two-thirds of the members of the Council shall constitute a quorum for the transaction of business. Nothing in the Charter shall prevent a smaller number from transacting business by a majority vote of members present to the extent necessary to fill vacancies in the membership of the Council in the manner provided in Article IV, where no quorum can be assembled except by filling the vacancies. Except as otherwise provided in the Charter, action by the Council shall be taken by a majority vote of the entire membership of the Council. Whenever in the Charter a certain proportion of the Council is required for the performance of any act, it shall mean that proportion of the entire membership of the Council.