2sin(x) - 1 =0
first, simplify and isolate sin(x)
2sin(x) - 1 = 0
2sin(x) = 1
sin(x) = 1/2
Then, do sin inverse of 1/2 which is 30 degrees
150 degrees also works because when you set 30 degrees as the reference angle in quadrant 2, you get 150 degrees. 180-30 = 150
C is the answer