Question

The length of a rectangular swimming pool is twice as long as its width. If the perimeter of the pool is

Answer 1

The perimeter of a rectangle is the sum of its sides, which are two widths and two lengths:

$p=w+w+l+l$

Since the length is twice the width, we have $l=2w$, and the formula for the perimeter becomes

$p=w+w+2w+2w=6w$

So, we have

$6w=120 \iff w=\dfrac{120}{6}=20$