Given:
two-Proof are given and it should be named.
Above proof is by Definition of segments.
Above proof is by Definition of segments.
Above proof is by Segment of Addition Postulate.
Above equation is wrong actually it is VX+XZ=VW+WY
and it is by Addition Property of Equality
Above equation is by Substitution Property (2nd use)
Above equation is by Substitution Property.