So for the rectangle part you work out the area which is length x width. So you do 5*4 =20. To work out the semi circle you need to know the area for a circle. The equation is pi*r^2. So you do 3.14*(2)^2. R is the radius in the equation. The radius is half the diameter so you divide 4 by 2 to get that. So the answer to the semicircle is 12.56. Finally you need to add them together. So the answer is 32.56.