If a farmer has pigs and chickens for a total of 20 animals with 54 legs, how many of each animal does he have?

Question

There are pigs and chickens in a barnyard.

There are 20 animals in the barnyard total.

They counted 54 legs.

How many of each animal above was in the barnyard (how many pigs, how many chickens)

 

Answer 1

say there are p pigs and c chickens

then p+c = 20.  So, c = number of chickens = 20 - p

and they have 4p+2c = 54 legs

substitute 20-p for c:

4p + 2(20-p) = 54

4p +40 -2p = 54

2p = 14

p = 7

c = 13