Answer:
PS = RT, PQ = ST Give?
PQ+QS=PS Segment Addition
ST+QS=RT False - should be ST + QS = PS by Substitution
RS+ST=RT Segment Addition
ST+QS=RS+ST Equal of equals are equal
QS=RS Subtraction Property of Equality
Because of the error in 3 the proof is incorrect, i.e. QS ≠ RS
Explanation: