Group $1$ of each kind of animals together, and there are $4+4+2=10$ legs in each group. There are $250\div10=25$ groups, so there are $25$ sheep. 
In a farm, there is an equal number of cows, sheep, and chickens. These animals have $250$ legs in total. How many sheep are there? 
a) $$18$$ 
b) $$23$$ 
c) $$25$$ 
d) $$33$$ 
e) $$38$$ 