Geometry
posted by Christina .
A rectangular swimming pool that is 12ft by 15 ft has a deck of uniform width built around it. If the area of the deck is 198 square feet, find its width.

(12 +2w)(15 + 2w)= 198 + 180
4w^2 + 54 w  198 = 0
2w^2 + 27w 99 = 0
(2w + 33)(w  3) = 0
w = 3 ft