Question

Yet again I still get confused

Answer 1

The left side is a half circle.
 The area of a circle is PI x r^2

The diameter of the circle would be the height of the rectangle, given as 10 feet.
 The radius is 1/2 the diameter, so 5 feet.

The area of half the circle is  (3.14 x 5^2) / 2 = 39.25 square feet.

The area of the rectangle is  20 x 10 = 200 square feet.

Total area = 200 + 39.25 = 239.25 square feet.