Answer:
90 ft
Explanation:
first you find the area of the 10 by 3 triangle, since on the other side it,s the same, all we need to do is find one of each triangle then mulitply it by 2 to get the area. then find the area of the 20 by 3 triangle. once you do that you will get 45, then you multiply it by 2 because it is the exact same on the other sides. then when you do that you get 90 ft. I hope this helps you! peace out.