Question

the ratio of dogs to cats in the pet store is 3/5. how many cats are there in the store if there are 21 dogs

Answer 1

Let the number of cats be as x

Ratio = 3:5
3:5 = 21 : x
3/5 = 21/x
x= 21 * 5/3
x= 5* 7
= 35 cats..

Answer 2

X - the number of cats

The ratio of dogs to cats is 3:5, and there are 21 dogs.
$\frac{21}{x}=\frac{3}{5} \\ 3x=21 \times 5 \\ x=7 \times 5 \\ x=35$

There are 35 cats in the pet store.