Two-thirds of the elected members of said convention shall constitute a quorum to do business, and a majority of those elected shall be sufficient to adopt or reject any proposition coming before the convention. If such majority votes in favor of the ratification of the amendment submitted to the convention, the said amendment shall be deemed ratified by the state of Washington; and if a majority votes in favor of rejecting or not ratifying the amendment, the same shall be deemed rejected by the state of Washington.