The equation for speed is distance/time. If the ends of the blades have to travel a farther distance due to the greater diameter of the blades the angular speed will decrease. Angular speed = larger number / original time
I'm assuming you're looking for the measure of angle y. Rule is that angle y will be equal to 1/2 of its intercepted arc. That arc measures 360-160-60 which is 140. Half of 140 is 70. So the first choice above is the one you want.
