Please help me!! Thank youu

Can someone me do math because i am having a breakdown rn because i don’t get it

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.

Solve -.016x= -16. need solving this