let's firstly notice, those are all the exterior angles of that polygon.
sum of all exterior angles in a polygon is always 360°.
[tex]\bf (9x-15)+(67)+(11x-5)+(4x+29)+(61)+(6x+13)=360 \\\\\\ 30x+150=360\implies 30x=210\implies x=\cfrac{210}{30}\implies x=7[/tex]
