The measure of angle b 65.8 find the measure of the complement and supplement angle

114.2 degrees
Assuming this is on a flat surface, there are 180 degrees in a semicircle. That means if out of 180 degrees an angle takes up 65.8 degrees, then there must be 114.2 degrees left. The equation would look like the following.

180-((angle)+(if other angles))= Left over amount.

Your equation specifically looks like the following.
180-65.8=114.2