Question

Which is the formula for finding the sum of the interior angles of a polygon?

Answer 1

It would be 
180(n – 2) where n is the number of sides 

Answer 2

The number of sides would be 180(n-2), we can test this theory with a triangle (interior angles add up to 180). A triangle has 3 sides so:

180(1) = 180

Therefore, the aforementioned equation is valid!