Imagine you're cutting off all of the slanted sides, there would be 3. Now since there's 4 feet on one side and 9 on the other when you cut off the edges they have side which are 3 feet (the end number) and 2.5 (9-4=5/2=2.5) now since you have three pieces like this, so put 2 together and you get a shape which is 3feet by 2.5 feet. The area of this is 3*2.5 which is 7.5, cut that in half for the third piece and you get 3.25, added together that's 10.75 squared feet. Now don't forget the 3 by 4 and 3 by 5 pieces. That would be a total of 27 (3*4=12 3*5=15) 27+10.75=37.75 squared feet. Let me know if I made a mistake any where :)
