Need help, dont understand

Question

A circular grass plot 12 feet in diameter is cut by a straight gravel path 3 feet wide, one edge of which passes through the center of the plot. Find the area of the remaining grass area

Answer 1

a) 12 - 3 = 9. This will make the diameter change from 12 units to 9 units.

b) The area formula of a circle is A = 3.14 x radius square

c) (3.14)(4.5)(4.5) = 63.585 units squared