Lines l and k intersect forming two pairs of vertical angle. If one of these angles measure 120°, what are the measures of the other three angles?

If one angle in the pair is 120°, the other one (on the opposite side) also has to be 120°. Which means that the remaining two (that are identical) you can get by subtracting 360° - 2*120° = 120° and by dividing that by 2, you'll get that remaining angles are 60° each. So, the remaining angles are 60°, 120° and 60°