Question

Jean stocked her aquarium with 36 fresh-water fish, which cost $212. The male fish cost $5 each, while the female fish cost $7 each. Find the number of male fish (x) and the number of female fish (y).

Answer 1

Male Fish = 20

Female Fish = 16

Explanation:

Let number of male fish be x and number of female fish be y

There are 36 fishes in total, so we can write:

x + y = 36

or

x = 36 - y

Also, male fish (x) cost 5 each and female fish (y) cost 7 each totalling $212, so we can write:

5x + 7y = 212

Now, we can put 1st equation in 2nd equation and get an equation in "y" and solve for y first:

`5x + 7y = 212\\5(36-y) + 7y = 212\\180-5y+7y=212\\2y=212-180\\2y=32\\y=(32)/(2)\\y=16`

We know x = 36 - y, so

x = 36 - 16

x = 20

Thus,

there are

20 Male fishes & 16 female fishes in the aquarium