What is the relationship (and ultimately the equation) between the number of sides of a regular polygon and the interior angle measure.

1) First determine the relationship between the number of sides of a regular polygon, n and the number of triangles that can be made.
2) Considering the triangle angle sum theorem tells us that the sum of all interior angles of a triangle are 180 degrees, what can we say about the sum of all of the interior angles in a regular polygon?
3) In a regular polygon, all interior angles are the same measurement. Knowing this, how can we find the measure of a specific interior angle of a regular polygon?
4) What is the interior angle measure of an octogon?
5) The interior angle of a regular polygon is 157.5 degrees. How many sides does it have?