There are 13 animals in a barn. Some are chicken and some are pig. There are 40 legs in all. How many of each animal are there?

Answer 1

Let x = the number of pigs

Let y = the number of chickens

We can make one question from the number of animals

x+y=13

Then, we can make another equation from the number of legs

4x+2y=40

This system of equations can be solved by substitution or elimination. I will use elimination by multiplying the first equation by -2

-2(x+y=13) Add the result to the second equation

-2x-2y=-26

4x+2y=40

2x=14 Divide both sides by 2

x=7

Using the first equation, we can solve for y

x+y=13

7+y=13

y=6

There are 7 pigs and 6 chickens.