For this case, the first thing we are going to do is rewrite the expression of the pool area again.
We have then:
(80 + 2W) (50 + 2W) - 80 (50) = 2,000
Rewriting we have:
4000 + 160W + 100W + 4W ^ 2 - 4000 = 2000
4W ^ 2 + 260W - 2000 = 0
W1 = 6.949334595148748
W2 = -71.94933459514874 (ignore)
round:
W = 6.95
Answer:
the width of the sidewalk should be:
W = 6.95 feet