Hey can someone me with just number 13 ?

At the "no mutants allowed" country farm, every sheep has 4 legs, every chicken has two legs, and all animals have only 1 head. asked to count how many sheep and chicken are in the fields, a farm boy reports back that there are 140 feet and 50 heads. how many sheep and chicken are there? there are sheep and chicken at the farm.

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14

Assume that y varies inversely with x. if y=1.6 when x=0.5 find x when y=3.2