Answer (with explanation):
1. Given
2. UY ≅ WY
3. Definition of Midpoint
4(statement). ∠UYX ≅ ∠VYW
4(reason). Side-Angle-Side SAS
5. Vertical Angle Theorem
in most proofs, (almost ALL the proofs) the first reason is always given.
you need given before you do anything.
on 2., the reason is Definition of Midpoint so you can tell it's UY is congruent to WY (uses the theorem)
on 3., it's the other way around and similar to 2. so the answer is definitely Definition of a Midpoint
on 4. statement and reason, you're side UY, angle Y, and side YX to prove that side VY, angle Y, and side YW are congruent. so, use the ∠UYX ≅ ∠VYW with the SAS
and on 5., you use vertical angles to say that ∠UYX reflects to ∠VYW so they are the same (aka congruent)