On his farm ol macdonald has 10 animals consisting of pigs and chickens. if there are 17 pairs of legs how many pigs and how many chickens are there?

A chicken has 1 pair of legs, and a pig has 2. If we have 10 animals, our equations are:

x + y = 10

x + 2y = 17

x is the number of chickens and y is the number of pigs

Subtract the two equations:

y = 7

This means that there are 7 pigs. 10 animals-7 pigs=3 animals remaining. There are three chickens remaining. To double check our answer, we can figure that 7*2=14+3 (the 3 pairs of chicken legs) = 17.