Something is very screwy about this, but I can't figure out what it is. I think it has something to do with the way the graph is drawn with some slight distortions. This is what I was able to find.

The whole triangle, which is made up of the 4 shapes colored red, mustard, light green and dark green, has the area of 1/2 x 13 x 5 = 32.5.

The area of the red triangle is 1/2 x 8 x 3 = 12
The area of the mustard shape is 7
The area of the light green shape is 8
The area of the dark green triangle is 1/2 x 5 x 2 = 5
The total of the four shapes is 12 + 7 + 8 + 5 = 32

The bottom triangle has the four shapes plus one empty square, so the sum of the components is 33, but we know the area should be 32.5.

The top triangle has just the four shapes so the area should be 32, but we know it is 32.5.

So in both cases, top and bottom, it is not what it seems to be, that is why I believe that there is a distortion in the way the shapes are drawn, to be off 1/2 a square on either top or bottom.