Area of the shaded region is 540 – 65.25π.
Solution:
Length of the rectangle = 12 + 9 + 6 + 3 = 30 in
Width of the rectangle = 18 in
Radius of the larger circle () = 12 ÷ 2 = 6 in
Radius of the medium circle () = 9 ÷ 2 = 4.5 in
Radius of the smaller circle () = 6 ÷ 2 = 3 in
Area of the shaded region = Area of the rectangle – Area of the larger circle – Area of the medium circle – Area of the smaller circle
Area of the shaded region is 540 – 65.25π.