Question 812194
w = width


area = (length)(width)
10 = (w)(w + 1.5)
10 = w^2 + 1.5w
20 = 2w^2 + 3w
0 = 2w^2 + 3w - 20
0 = (2w - 5)(w + 4)
w = 5/2, w = -4


Distance has to be positive, so the mirror is 5/2 = 2.5 ft wide and 4 ft long.