Where a protest against any such amendment, supplement
or change is presented at or before the public hearing, duly signed
and acknowledged by the owners of 20% or more of either the area of
the lots included in such proposed change or the land immediately
adjacent to the rear thereof extending 100 feet therefrom, or of those
directly opposite thereto extending 100 feet from the street frontage
of such opposite land, such amendment shall not become effective except
by a favorable vote of all the members of the Board of Trustees.