The first thing you do is find the area of the rectangle, which is l*w or 9*4 = 36. Then you find the area of the circle, which is pi*r^2 or pi*2^2 or 4*pi (do not combine pi and 4 yet). Lastly, you would subract the area of the circle from the area of the rectangle. It would be 36-4*pi, which equals about 23.43 ft.