Use the AAS congruence rule to prove that the two given triangles are congruent.
The congruence of two of the corresponding angles is already given:

On the other hand, since O and Z lie in the segment YN, we know that:

And since YO=NZ (given), then:

Since two angles and one pair of corresponding sides are congruent, then, using the AAS correspondence rule, we can conclude that the triangles MNO and XYZ are congruent.