The answer is a. What you need to do is find the area of the shape if it were a perfect rectangle - (20)(16)=320 in^2. Next you make an imaginary square in the corner (it's a square because it's 8in by 8 in) and find the area - 8^2 or (8)(8)=64. Finally you subtract the values - 320 - 64 = 256 in^2 voila.
