Question

1/3 of the total barn animals were chickens and rest were pigs there were total 20 legs. How many were pigs?

Answer 1

4P + 2C= 20 (the number of legs), and
C = P/2 (since 1/3 are chickens)

Therefore

4P + P = 20
P = 4 is the number of pigs, and
C = 2