The Lincoln Animal Shelter currently only has dogs and cats at the shelter. If the ratio of dogs to cats is 1 to 2, and there are a total of 21 animals at the shelter, how many of the animals are dogs?

2 answers

Help me please
let the number of dogs be x
let the number of cats be 2x
(note that dogs:cats = x:2x = 1:2)

x + 2x = 21
3x = 21
x = 7
so you have 7 dogs and 2x or 14 cats

check:
note dogs:cats = 7:14 = 1:2 , and 7+14 = 21
so all is good.