The question is asking you to find the measure of YZ's arc.
The arc of a circle is found by finding the central angle. In this case, that's angle YCZ. Remember that a circle's total degrees is 360. Since the angle that you are trying to find is 16% of the circle, you need to find 16% of 360.
360*0.16 = 57.6
The measure of arc YZ is 57.6 degrees.