for the rectangle you add 12 plus 9 to get 21 then multiply by 24 to get 288. then. you multiply 15 times 9 to get 135 then divide by 2 to get 67.5 for the top triangle. you then add 12 and 9 together to get 21 and multiply that by 15 to find the middle rectangle then you get 315. you then add all of the final values together to get 670.5 square units
