Use the formula for solving the sum of degrees of the interior angles, then divide by \(n\) to find out only one of the interior angles.

Use this formula: \(\frac{(n-2)\times180}{n}\)

I'll do the first one:

\(n=3\)

\(\frac{(3-2)*180}{2}=\frac{180}{2}=90\)

90 is an integer, so 3 will not work.

Keep on doing this until you get to 9.