Step-by-step explanation:
length * breadth * height = volume
plug it in
9 * 10 * height = 1800
height = 1800 ÷ 90
height = 20
2lw+2lh+2hw = surface area
breadth = width = w
plug it in
(2 * 9 * 10) + (2 * 9 * 20) + (2 * 20 * 10) = surface area
940 = surface area
