The slanted area has the bottom length of 8 if you take it off the bottom length would be 15. 15 times 11 is 165. Now you figure out the area of the slanted area which is basically a triangle. Its half a square, if it was a square its area would be 88 but since its only half a square its only half of 88 which is 44.
165 plus 44 = 209 so the answer is 209 ft.
