bear in mind that the area of a "parallelogram" is base * height.
notice the picture, the front and back parallelograms, have an altitude/height of 3 cm, and a base of 8 cm, so the area of one of those two is 3*8.
as far as the left and right parallelograms, they have a base of 7 cm, but the altitude is also 3 cm, so the area of one of those is 3 *7.
bear in mind the altitude/height is the distance from the base to the top, and in this case is just 3 cm.
anyway, you have 4 parallelograms, get the area of each, add them up, and that's the surface area of the figure.
2(3*8) + 2(3*7).