Practice!

Sample Problem

The ratio of the number of dogs to cats to birds in a pet shop is 9:6:10. The number of dogs and cats is 45 altogether. If 10 dogs, 7 cats and 8 birds were sold, how many of the three kinds of pets remain?

Dogs:

Cats:

Birds:

Solution

Set the number of dogs as 9 units, cats as 6 units and birds as 10 units. So, the sum of dogs and cats is (9 + 6 = 15) units. Then,

15 units = 45

1 unit = 45 ÷ 15 = 3

9 units = 9 × 3 = 27

6 units = 6 × 3 = 18

10 units = 10 × 3 = 30

Thus, the remaining number of pets of each kind:

Dogs: 27 - 10 = 17

Cats: 18 – 7 = 11

Birds: 30 – 8 = 22