The city council may from time to time amend, supplement, or change by ordinance the boundaries of the districts or the regulations herein established.

Before taking action on any proposed amendment, supplement or change, the city council shall submit same to the planning and zoning commission for its recommendations and report.

A public hearing shall be held by the city council before adopting any proposed amendment, supplement or change. Notice of such hearing shall be given by publication three (3) times in the official publication of the city, stating the time and place of such hearing, which time shall not be earlier than fifteen (15) days from the first date of publication or by certified mail.

Unless such proposed amendment, supplement or change has been approved by the planning and zoning commission, or if a protest against such amendment, supplement or change has been duly filed with the city secretary, duly signed and acknowledged by the owners of twenty (20) percent or more of the area of the lot included in such proposed change or within two hundred (200) feet from any point of the proposed change in any direction, such amendment shall not become effective except by a three-fourths (¾) vote of the city council.