Answer:
D) 1260°
Step-by-step explanation:
In an n-sided polygon, the sum of all angles is equal to (n-2)*180°.
Look at it this way - let's add a point in the middle and connect it to each vertex. Then we've got n triangles for a total of n*180°, but all of the angles at the middle point aren't "part" of the polygon, so a full 360° angle should be subtracted, giving us n*180°-360° = (n-2)*180°
You can easily confirm that it works for triangles and quadrangles ;)
The figure in the picture has 9 sides, so the sum of angles is (9-2)*180° = 7*180° = 1260°