You know that the sum of the angles in a triangle is 180 degrees, so to find the missing angle in the triangle, subtract 180 from the sum of the other 2 angles: 180-(52+98)=180-150= 30 degrees.
You also know that the sum of supplementary angles is 180, and there are 2 supplementary angles. since we just found one of the angles, all we need to do is subtract 30 degrees from 180 degrees: 180-30= 150 degrees. (x is 150 degrees)
