You need to find the area of the semi circle first which the formula is (pi)r^2/2. So 3.14159 ·(8)^2/2 is 101. Then find the area of the rectangle and subtract the area of the semi circle from the area of the rectangle! I hope this helps, I use ALEKS too. (I got 251 as a final answer, I'm p sure it's correct)
