Question 1016172
Length = width + 40
Set w = width
Area = length * width
6000 = (w + 40)(w)
6000 = w^2 + 40w
add -6000 to each side
0 = w^2 + 40w -6000
0 = (w-60)(w+100)
w = 60 or w = -100
Since we need a positive width, w = 60 and length = 100