See angle AOC.
It starts at the horizontal 180 degrees and goes to 150 degrees.
It is an acute angle.
Thus, it's measure is:
180 - 150 = 30 degrees
Thus,

Now, see angle COE.
It starts at 150 degrees and entends to 40 degrees. It is an obtuse angle (greater than 90). Thus, the angle is:
150 - 40 = 110 degrees
Thus,
