What you should know: ¼ of a circle is called a quadrant.
½ the width of 280ft of the rectangular plot is 140ft as stated in the image. Therefore 140ft is the radius of the circle.
¼ of a circle formula = ²/4
3.14 x 140²/4
15,380 in area
area of rectangle: length x width
300 x 280
84,000
Subtract the quadrant’s area from the rectangle’s area to get the area of the grass: 84,000 - 15,380 = 68,620