[Math] how to find number of sides of an irregular polygon

Question

An irregular polygon has one angle 126 degrees and the rest 162 degrees. how many sides are there in this irregular polygon?

I have tried to find our the sides with the formula of a regular polygon; obviously it doesn't work.

Answer 1

Using the formula of the sum of interior angles

$$162(n-1) + 126 = 180(n-2) \Rightarrow n=18. $$

Remark: I assume a simple and plane polygon.