#3/4# is a fraction meaning it is only a part of a whole. In decimal form it's #0.75# or #75%# as a percent.
By definition, whole numbers include #0#, counting numbers #1,2,3,...#, and integers e.g #-4,-3,-2,...,1,2,3,4,5,...#
Another way to think about whole numbers is to think about cake. Say we cut the cake in #4# equal pieces. Each piece of cake now represents #1/4# of the cake which is just a fraction of the cake, not the cake as a whole. If we combine all four pieces of cake together #(1/4+1/4+1/4+1/4)# we get #4/4# pieces of cake or #1# whole cake since we initially had #1# cake that we split into #4# pieces
To learn more about whole numbers visit: https://www.mathsisfun.com/whole-numbers.html