When a petition is filed, signed by registered voters of an incorporated city or town, in number equal to not less than fifty percent of the votes cast at the last general municipal election, seeking the adoption by the city or town of the classification of noncharter code city, either under its existing authorized plan of government or naming one of the plans of government authorized for noncharter code cities, the county auditor shall promptly proceed to determine the sufficiency of the petition under the rules set forth in RCW
35A.01.040. If the petition is found to be sufficient, the county auditor shall file with the legislative body a certificate of sufficiency of the petition. Thereupon the legislative body of such city or town shall, by resolution, declare that the inhabitants of the city or town have decided to adopt the classification of noncharter code city and to be governed under the provisions of this title. If a prayer for reorganization is included in the petition such resolution shall also declare that the inhabitants of the city or town have decided to reorganize under the plan of government specified in the petition. The legislative body shall cause such resolution to be published at least once in a newspaper of general circulation within the city or town not later than ten days after the passage of the resolution. Upon the expiration of the ninetieth day from, but excluding the date of, first publication of the resolution, if no timely and sufficient referendum petition has been filed pursuant to RCW
35A.02.025, as now or hereafter amended, as determined by RCW
35A.29.170, the legislative body at its next regular meeting shall effect the decision of the inhabitants, as expressed in the petition, by passage of an ordinance adopting for the city the classification of noncharter code city, and if the petition also sought governmental reorganization by adoption of one of the plans of government authorized for noncharter code cities involving a different general plan of government from that under which the city is operating, then the legislative body shall provide at that time for such reorganization by ordinance and for election of all new officers pursuant to RCW
35A.02.050, as now or hereafter amended.