The shaded figure is a parallelogram. The formula for determining the area of a parallelogram is expressed as
area = base * height
Height = 7 mm
base = 8 mm
Area = 7 * 8 = 56 mm^2
Inside the shaded paralelogram is a rectangle which is unshaded. The area of the rectangle is
5 * 3 = 15 mm^2
Area of shaded figure = 56 - 15 = 41 mm^2