Statements are (underlined) and reasons are (bolded).
It is given that (<W) and (<Y) are both right angles, therefore, they must be congruent since they have the same angle measures.
<W = <Y definition of right angles
Moreover, it is given that (VX) and (ZX) are congruent.
VX = ZX given
Finally, it is given that (x) is the midpoint of (WY). Therefore, (WX) is congruent to (XY), and therefore, they are congruent.
WX = XY definition of midpoint
Thus, triangle (YWX) is congruent to (ZYX) by the following rule, side-angle-side, also known as (SAS).
YWX = ZYX SAS
When two sides and an angle are congruent between two or more triangles, then those triangles must be congruent.