The length of a rectangular field is 20 less than its width. the area of the field is 12,000 ft2. what is the width of the field? 80 ft 100 ft 120 ft 140 ft

Area = length*width

12000 = (width - 20) * width

let width be w

12000 = (w-20) * w

w^2 - 20w - 12000 = 0

w^2 + 100w - 120w - 12000 = 0

w (w+100) - 120 (w+100) = 0

(w+100) (w-120) = 0

w+100 = 0, w-120 = 0

w = - 100, w = 120

but the width of a field cannot be negative!

hence,

w = 120.

Width of the field is 120ft.