Question 385315
You have two variables, number of chickens and number of pigs. This means you need to algebra equations.


Let c = number of chickens
Let p = number of pigs


We know that there are 13 heads in total, so that means that:


c + p = 13


(Because each chicken and pig has one head each!)


We also know that there are 36 feet. Chickens have 2 feet, while pigs have 4 feet:


2c + 4p = 36


Now you have your two equations. Solve them with elimination or substitution.


c+p=13
2c+4p=36


Multiply the first equation by 2, then subtract:

2c+2p=26
2c+4p=36
---------
0 - 2p = -10

p = 5


Now find c:

c = 13 - p
c= 13-5
c = 8


So there are 8 chickens and 5 pigs.