To calculate the exterior angle of a regular polygon, we have to divide 360 by the number of sides on the polygon
Angle a is the exterior angle on a regular hexagon, which has 6 sides.
So, to calculate the exterior angle, we use 360/6 = 60 degrees
To calculate angle b, which is an interior angle, we calculate the exterior angle and subtract it from 180. This is because angles on a straight line add up to 180 degrees
Angle b is an interior angle of an octagon, which has 8 sides. So, we use
180 - (360/8) = 180 - 45 = 135 degrees.
Hope I helped! xx