For each pair, give the relationship between the two compounds. Making models will be he...

For each pair, give the relationship between the two compounds. Making models will be helpful.

(a) (2R,3S)-2,3-dibromohexane and (2S,3R)-2,3-dibromohexane

(b) (2R,3S)-2,3-dibromohexane and (2R,3R)-2,3-dibromohexane