Question

A rectangular pool is 20 feet wide and 50 feet long. The deck surrounds the pool and is the same width around the pool. The total area. Of the deck is 456 square feet. How wide is the deck around the pool?

Answer 1

(20+2x)(50+2x) - 20(50) = 456
expand
1000 + 40x + 100x + 4x² - 1000 = 456
combine like terms
4x² + 140x - 456 = 0
divide everything by 4
x² + 35x - 114 = 0
use quadratic equation
x is -38 or 3.

The answer must be positive 9distance cannot be negative)
 so the answer is 3ft wide