The sum of the interior angles of an octagon is 1080 degrees.

First, we calculate the angle of the regular octagon 90 + 45 = 135 degrees Then, 135 x 8 = 1080 degrees

What geometric figure could be constructed from the difference in the sums of the internal angles of an octagon and a pentagon?

In the image below, what is the sum of the gray angles (in degrees)?