Well the sum of the exterior angles of any perfect polygon has to be 360 degrees. Therefore the exterior angles of an 8 sided polygon are 45 degrees (360/8). The interior angles are each 135 degrees (180-45) as the exterior and interior angles arecomplementary angles.

just remember, its always 360 divided by the exterior angle to find the number of sides.. so 12

Exterior angles are supplementary with interior angles, so 180-30=150