Aconjecture and the two-column proof used to prove the conjecture are shown. given: s is the midpoint of segment r t. segment r t is congruent to segment x y. prove: segment r s is congruent to segment x y. segment x y with endpoints x and y. line r s t is horizontal. line r s t has two segments r s and s t with the same length. s is the midpoint and r and t are the extreme left and extreme right points respectively. drag an expression or phrase to each box to complete the proof.