a.
7 cats      c
____ Â Â = Â Â ____
15 animals    300 animals
b.
7 Â Â Â c
_ = Â _
15 Â Â 300
c = 140
There are 140 cats in the Humane society since 15 x 20 = 300 and 7 x 20 = 140
a. doesn't need an explanation really, 7 cats for 15 animals and c cats for 300 animals