How many of each animal are there ?

Question

There 17 anim in a barn. Some are chickens some are pigs. There are 58 legs in all. How many of each animal are there?

Answer 1

P + C =17 (# of Pigs plus # of chickens is 17)

4P + 2C  = 58  (Each pig has 4 feet and each chicken has 2 feet)

 

 

We can solve this system by multiplying the top equation by 2

 

2(P+C=17) = 2P+2C=34

 

We will compare this to the equation 4P+2C=58

 

4P+2C=58

2P+2C=34

 

Subtract equations (Cs cancel --eliminate)

 

2P = 24

 

divide by 2

 

P = 12  (We have 12 pigs)

 

And since we had 17 heads we must have 5 Chickens