Wash. Rev. Code § 35A.12.120
At all meetings of the council a majority of the councilmembers shall constitute a quorum for the transaction of business, but a less number may adjourn from time to time and may compel the attendance of absent members in such manner and under such penalties as may be prescribed by ordinance. The council shall determine its own rules and order of business, and may establish rules for the conduct of council meetings and the maintenance of order. At the desire of any member, any question shall be voted upon by roll call and the ayes and nays shall be recorded in the journal.
The passage of any ordinance, grant or revocation of franchise or license, and any resolution for the payment of money shall require the affirmative vote of at least a majority of the whole membership of the council.
RCW 35A.12.120