In this problem, we are dealing with vertical angles.
Note that when two lines intersect,
they will aways form two pairs of vertical angles.
Vertical angles are always congruent.
We can setup the equation 4x - 101 = 2x + 3.
Subtract 2x from both sides to get 2x - 101 = 3.
From here, you should be able to easily finish the problem.
We find that x = 52.