The question needs a diagram. Triangles can be congruent, not angles. In two congruent triangles, that is triangles having the same dimensions, all the angles in one triangle match the corresponding angles in the other triangle. You mention the angle TXT, but that can't be an angle because there are two T's. So I'm going to guess what the picture should be and that the angle you're talking about should be YXT.
The two triangles are WXT and YXZ and they're joined together at X. The two triangles are congruent, we're told, and angle WXT=angle YXZ. The angle ZXW=angle ZXT+angle WXT. Angle ZXT is the angle between the side XT of one triangle and the side XZ of the other triangle. The angle YXT=angle ZXT+angle YXZ. So there's a shared component. We know angle WXT=angle YXZ, so angle YXT=angle ZXW.