HELp

His speed was 2m/s, and his velocity was 2m/s south.

Explanation:

"Round trip" means that they go somewhere and then they travel back to where they were. this means that although the distance was 200m from the library, he actually traveled 400m (200m one time to go to the library, 200m another time to go back). His velocity would be south because at the end of his trip (when he is heading back to his original location) he would be traveling south instead of north.