A rectangular building is to be built on a lot measuring 46m by 30m. The building will be surrounded by a strip of lawn of uniform width. If the lawn takes up 30% of the lot, how wide will the lawn be?

Answer 1

length = 46 + 2w
width = 30+2w
building area = (46-2w)(30-2w)
0.7 * lot area = building area
0.7*46*30 = (46-2w)(30-2w)
multiply it out and solve quadratic