Protest. In case of protest against a change duly signed and acknowledged by the owners of 20% or more either of the area of land included in such proposed change, or by the owners of 20% or more of the area of land immediately adjacent and extending 100 feet therefrom, or by the owners of 20% or more of the land directly opposite thereto extending 100 feet from the street frontage of such opposite land, and filed with the City Clerk no later than the close of work the day preceding the Common Council vote on the change, such change shall require a favorable vote of 3/4 of the Common Council for passage.