Hello, ClutchUSMC!

You are putting in a 20ft x 30ft rectangular pool.

Your pool will be surrounded by a concrete sidewalk of uniform width and 3 inches thick.

Write an expression in terms of for the volume of concrete in the sidewalk.

Explain how you got your expression. I assume that is the width of the sidewalk. Code:

: x : - 30 - : x :
- * - - - - - - - - * - -
x | | :
- | * - - - - * | :
: | | | | :
20 | |20 | | 20+2x
: | | 30 | | :
- | * - - - - * | :
x | | :
- * - - - - - - - - * - -
: - - 30+2x - - :

The total area is: . ft²

The pool area is: . ft²

The area of the sidewalk is: . ft²

The thickness of the sidewalk is: .

Therefore, the volume of the concrete is: . ft³