mathematics homework problem

Question

A swimming pool has a 3-foot wide cement walkway around its perimeter as shown.

Write a simplified expression that represents the area (in square feet) of the cement walkway.

Answer 1

outside square's area minus inside square's area

(4x+2+6)(12+6) - (4x+2)(12)

=(4x+8)(18) - 48x -24

= 72x -48x +144-24

= 24x +120 square feet = walkway area

is one way to do it

or

4(3^2) + 2(4x+2)3 + 2(12)3=4 small square corners + 4 rectangular strips above, below, left & right of pool

=36+ 24x+12+ 72

= 24x +120 ft^2= same area adding up 8 sections of the walkway