Each straight line is 180 degrees, keep that in mind! subtract 150 from one side (subtract it from 180) and the other side must at most be the remaining degrees out of the 180 total.
In part A, the angles are Vertical Angles and are, therefore, congruent. This means you set them equal to one another and solve for X. For part B, the angles are supplementary angles which means they equal 180 degrees.
