I am going to make what is hopefully not an incorrect assumption and say that since the segmentXSZ is black and the other lines are blue, that XS is congruent to ZS. If that be the case we have a side in each triangle that is congruent to each other and an angle that is marked as congruent. Angles XSW and ZSY are vertical angles. By definition, vertical angles are congruent. In each triangle, then, we have an angle, a side and an angle which gives us the congruency postulate ASA.
