The sum of the angle measures of a polygon with n sides is 1260. Find n.

The sum of the angle measures of a polygon with n sides is 1260.

Find n.

$\begin{array}{|rcll|} \hline (n-2)\cdot 180 &=& 1260 \quad &| \quad : 180 \\ n-2 &=& \frac{1260}{180} \\ n-2 &=& 7 \quad &| \quad +2 \\ \mathbf{n} & \mathbf{=} & \mathbf{9} \\ \hline \end{array}$