A farmer has x pigs and y chickens. Write an expression for how many head? Write an expression for how many legs?

Question

Can someone please explain the method for getting the answer to the second one and what the answer is? Thanks

Answer 1

Let x = the number of pigs and y = the number of chickens.  Since each pig and chicken has one head, the number of heads is:

 

number of heads = x + y

 

Each pig has 4 legs while each chicken has two.  So the number of legs is:

 

number of legs = 4x + 2y

 

So if you have 2 pigs and three chickens, you have

 

number of heads = 2 pigs + 3 chickens = 5 heads

number of legs = (4 legs per pig)*(2 pigs) + (2 legs per chicken)*(3 chickens)

= 8 + 6 = 14 legs in all