a cement walk of constant width is built around a 20ft by 40

a cement walk of constant width is built around a 20-ft by 40-ft rectangular pool. The total area of the pool and the walk is 1500ft sq. Find the width of walk

Solution

(20 + x) (40 + x) = 1500

x represents the additional width you are looking for.

I do not know your educational background. I am therefore going to assume you have not yet learned FOIL.

FIRST...20 x 40 = 800
OUTER...20x
INNER...40x
LAST...(x)(x)=x2


The equation is now...
800 + 20x + 40x + x2=1500

Let\'s simplify and subtract 800 from both sides...

-800 + 800 + 60x+ x2=1500-800

Simplify...

60x + x2=700

The answer can only be obtained through visual inspection. I tried everything to isolate the x and calculate.

x=10 feet.