Hi there!
This is the formula for finding the sum of interior angles for a polygon with a number of sides "n".
We can also prove this from the table:
Triangle ⇒ 3 sides: 180(3 - 2) = 180°
Quadrilateral ⇒ 4 sides: 180(4 - 2) = 360°
Pentagon ⇒ 5 sides: 180(5 - 2) = 540°
...And so forth. We can write this as for any polygon with "n" sides:
180(n - 2) = sum (°)