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Printjmc
prealgebra senior
Problem
A picture frame consists of two rectangular strips of wood, each having a width of 1 inch on all sides. If the area of the inner light gray strip is 100 , then compute the area of the outer dark gray strip in square inches. 
Solution
Imagine cutting the picture frame into pieces as shown.
Clearly the long light and dark gray strips along the four sides are identical, so they have the same area. The only leftover dark gray pieces are the four pieces in the corners. In other words, the dark gray part of the frame is 8 square inches greater than the light gray region, which means that it has an area of .
Clearly the long light and dark gray strips along the four sides are identical, so they have the same area. The only leftover dark gray pieces are the four pieces in the corners. In other words, the dark gray part of the frame is 8 square inches greater than the light gray region, which means that it has an area of .
Final answer
108