I believe the easiest way to do this would be to find the area of the rectangle without the piece missing, find the area of the piece missing and then subtract it.
So to find the area of a square/rectangle we need to multiply the length×width, so 40×36, and that is 1,440. For the piece missing it would be 20×10, which is 200.
Now all we need to do is 1,440-200, and that gives us our answer, 1,240!
The area of the figure is 1,240 yd, C.