Ok first-- Find the area of the rectangle. Then, find the area of the circle. The diameter is given, so take half that to get the radius. Multiply the area of the circle by half. Subtract the area of the half-circle from the area of the rectangle.
I'll do the first one as an example. The answer of the first one is 6.
In the first example, they multiplied the number by 2 to get a common denominator for the two fractions so you can easily add. So, the first box will come 10 (5 times 2) and the second box will become 2 (1 times 2). Then simply add the fractions. The sum of the first question is 2. Because 2 10/12 + 3 2/12 = 6. Remember to add only the whole numbers and fractions. If you want, you can try using mathaway for additional help.