There is a rectangle that is 18“ x 30“. There are three progressively smaller circles within the rectangle stacked on top of each other in the middle of the rectangle. The side length of the one on the bottom is 12 inches the side length of the one in the middle is 9 inch and the one on the top is 6 inch. There is a 3 inch space at the top. Every part of the rectangle, except for the circles are shaded. Find the area of the shaded region.