Area and perimeter

Question

The length of the pool is 5 times the width. If the are of the pool is 405 ft^2. What is its perimeter?

L=5w

A=Lw

P=2(l +w)

Answer 1

A=Lw, so A=(5w)w=5w^2, A=405

If we put them together, 5w^2=405 ==> w^2=405/5=81 ==> w=9

L=5w=5*9=45

P=2(l +w) =2(45+9)=2(54)=108 ft