The formula for the surface area of a rectangular prism (the storage box) is given by: A=2(wl+hl+hw). In this instance, w = width, h = height, and l = length.
We will calculate the surface area of the box and lid by first determining the height with the storage box lid included.
The height is now 40 cm (= 30 + 10). The width is still 45 cm. The length is still 60 cm.
You can fill in these values: A = 2(wl+hl+hw) = 2((45 * 60) + (40 * 60) + (40 * 45)) = 13,800.
