Regulations, restrictions, and boundaries may be amended, supplemented, changed, modified, or repealed from time to time. If a protest against a change, supplement, modification, amendment, or repeal is signed by the owners of twenty percent or more:
the amendment shall not become effective except by the favorable vote of three-fourths of all the members of the governing body of the city. The provisions of section 40-47-04 relating to public hearings, official notice, and publication of regulations, restrictions, and boundaries shall apply equally to all changes or amendments provided in this section; provided, that protests in writing must be filed with the city auditor prior to the time set for the hearing.
N.D.C.C. § 40-47-05