The area of the shaded region is 78 square inches. All angles are right angles and all measurements are given in inches. What is the perimeter of the non-shaded region?
The total area = 9 x 10 = 90 sq in
The shaded area = 78 sq in
Subtracting, the central area = 12 sq in
Since the height is 2 in, the width must = 6 in