I believe the area is 24 
Explanation: 
It’s easier if you break apart the shape into two shapes. You have a square and a rectangle. The square’s area will be L x W= A so 4 x 4 = 16. 
Now look at the rectangle and use the same formula L x W = A. The width is 2 and the length is 4 because we cut the whole bottom 8ft length in half when we solved the area for the square. So then the rectangle is 2 x 4 = 8 
Now add the two areas 16+8= 24 
Area =24 
This is how I do it