Question

the ratio of dogs to cats at the pet store is 1:4.if the pet shop has 7 dogs,how many cats does it have ?

Answer 1

$1:4=\frac{1}{4}\\\\d-number\ of\ dogs;\ c-number\ of\ cats\\\\d:c=1:4\to\frac{d}{c}=\frac{1}{4}\\\\d=7\ therefore\\\\\frac{7}{c}=\frac{1}{4}\ \ \ \ |cross\ multiply\\\\1\cdot c=7\cdot4\\\\\boxed{c=28}\leftarrow answer$