ABCDEFGH is a regular octagon. The minimum degree of rotation by which this octagon can map onto itself is
°. It will take
increments of that degree of clockwise rotation for A′ (the image of A) to coincide with C.

Question

ABCDEFGH is a regular octagon. The minimum degree of rotation by which this octagon can map onto itself is 
°. It will take 
 increments of that degree of clockwise rotation for A′ (the image of A) to coincide with C.

mhanifa · Answer

You need to find the angle x = 360/y, where y is the number of sides of the polygon.

mhanifa · Answer

The x would be the required angle measure for the rotation. that would map A with B' or B with A'.
Since C is the next vertex, you need to find the value of 2x for the second part of the question.