math
posted by Anonymous on .
a rectangular plot of ground having dimensions 46 feet by 30 feet is surrounded by a walk of uniform width. If the area of the walk is 240 ftˆ2, what is its width?

area w/o walk: 46*30 = 1380
area w/walk (46+2w)(30+2w)
So, we have
(46+2w)(30+2w)  1380 = 240
4w^2 + 152w + 1380  1380 = 240
4w^2 + 152w  240 = 0
w^2 + 38w  60 = 0
w = 19 + sqrt(421) = 1.5