Answer:
"genki desu ka?" = Are you well?
"hai, genki desu." Yes, I am well.
Explanation:
はい (Hai) = Yes
元気 「げんき」 (Genki) = Well, Lively
です (Desu) = A way to end a sentence formally.
か (Ka) = A question marker.
With the way Japanese sentences are structured:
"元気ですか?" = Well?
"はい、元気です" = Yes, well.
Remember that in japanese, pronouns are usually omitted.