To find the area of the shaded area, you need to take the area of the square minus the area of the unshaded circle.
The formula for area of circle is pi(r)^2, where r stands for radius. In this case, the radius of the circle is 10 yards and pi is 3.14. The area of the circle is thus:
area of circle: pi(r)^2
= 3.14 (10)^2
= 314
The formula for area of square is length times length. In this case, the length of the square is 20 yards. Area of square is thus:
Area of square: 20 X 20
= 400
The area of shaded area
= area of square - area of unshaded circle
= 400-314
= 86 yards^2 (option 2)
I hope this helps! Feel free to clarify if unsure!