the answer is C. I got that by taking the height of 13 in and multiplying it by 21 in or 13x21=273 in2. After that I took 13-9=4 to find the height of the triangle that is missing from the top of the rectangle. I took half of the height and mulitplied it by the base of 2x21=42. finally I took the total area of the rectangle which is 273 and I took the area of the triangle away from that or 273-42=231 in2. Hopefully this helps