Answer:
120
Explanation:
A reference angle is the angle it makes with the x axis,
120 makes a 60 degree angle with the x axis
(180-120) = 60 It is closer to the negative x axis
210 is closer to the negative x axis which is 180
210-180 = 30
-330 is closer to the positive x axis which is 0 or 360
-330 - (-360) = 30
-30 is closer to the positive x axis which is 0
-30 - (0) = -30
-30 but the angle itself is 30