These triangles are congruent by Angle-Side-Angle (ASA) Theorem. This is because they both share two corresponding congruent angles, being Angle U and Angle Y, and Angle VUW and Angle XYW (they're vertical angles, meaning they're congruent).
They also share a corresponding congruent side, being Side UW and Side YW. You can tell because of the congruent dash marks on the sides, that have already been given to you.
