Here is how you solve this:
1) If a line bisects an angle, then both angles are equal (This means that angle OLN and angle OLM are equal).
2) If 2 angles of 2 triangles are equal, then the sides opposite of each angle are equal (This means that, since angle OLN and angle OLM are equal, side NO and side OM are equal).
3) If NO=OM, then OM=4.
The answer is x=4.
