Let's split our shapes up to help us solve these problems. I will do A, and allow you to apply these skills learned to B.
Look for any shapes that you may be able to split the overall shape into. In this case, we can split the overall shape into a rectangle and a triangle. We can find the area of both of these shapes and then add them.
The rectangle has length 10 and width 8. Thus, its area is 8*10 = 80.
The triangle has base 4 (Subtract the 8 from the 12) and height 4 (Subtract the 6 from the 10). Thus, its area is (1/2)(4)(4) = 8.
We can now add these areas to get a total area of 88 units^2.