A black rectangular box is 8 inches longer than it is wide. A green rectangle box is 3 inches wider than the black box but it has the same length. The area of the green box is 39 square inches more than the area of the black box.

Answer 1

black: x(x+8)
green: (x+3)(x+8)

(x+3)(x+8) = x(x+8)+39