Explanation

A zoo has some lions and Parrots.

A zoo has x lions and y parrots

 The supervisor counted 15 heads and 50 legs. How many lions are there?

Heads

x + y = 15 

y = 15 – x

x = 4 legs and y has 2 legs

4x + 2y = 50

4x + 2(15-x) = 50

4x + 30 – 2x = 50

2x = 20

X = 20/2

X = 10

So x means lions, so there 10 Lions

CHECKING our answer***

  40 + 10 = 50 legs