1. Passage of an ordinance, amendment, or resolution requires a majority vote of all of the members of the council, except when the mayor may vote to break a tie vote in a city with an even number of council members, as provided in section 372.4. Passage of a motion requires a majority vote of a quorum of the council. A resolution must be passed to spend public funds in excess of one hundred thousand dollars on a public improvement project, or to accept public improvements and facilities upon their completion. Each council member‘s vote on a measure must be recorded. A measure which fails to receive sufficient votes for passage shall be considered defeated.
 2. A measure voted upon is not invalid by reason of a conflict of interest in a member of the council, unless the vote of the member of the council was decisive to passage of the measure. The vote must be computed on the basis of the number of members not disqualified by reason of conflict of interest. However, a majority of all members is required for a quorum. For the purpose of this section, the statement of a council member that the council member declines to vote by reason of conflict of interest is conclusive and must be entered of record.