bearing in mind that a NONA=9 gon, is a 9-sided polygon, thus
[tex]\bf \textit{sum of all exterior angles in a polygon}\\\\n\theta = 360~~\begin{cases}n=number~of\\\qquad sides\\\theta =angle~in\\\qquad degrees\\[-0.5em]\hrulefill\\n=9\end{cases} 9\theta =360\implies \theta =\cfrac{360}{9}\implies \theta =40[/tex]
