Answer: 700yd^2
Explanation:
Area of Square - Area of Triangle
Area of Square: 30^2 = 900yd^2
Area of Triangle: (20) (20) / 2 = 200 yd^2
from the left side we can see the whole side is 30yd long. On the right we see its only 10 yd, meaning the triangle takes up the remaning 20yds. The whole bottom line equals 40 yd. The top line is only 20yd, leaving the other 20yd for the triangle.
900 - 200 = 700yd^2