For a geometry test they asked for the sum of the exterior and interior angle formulas then asked what the sum represented. You have to use a n-gon. I want to make sure I'm right.

What I think it is:

Exterior- 360/n
Interior- (n-2)180/n

Sum- (n-2)540/2n

The sum is one interior and one exterior angle combined.

What you have writtem for both the interior and exterior angle formulas are correct only for regular polygons, where all angles are the same. With that caveat you need to check your addition: the sum of the two formulas is



If you draw a sketch of a corner of a polygon and note the interior and exterior angles you can see how they add to 180.