Answer:
a.
Explanation:
The following information is missing in the question:
What does 6 1/2 mean in this situation
a. Zhen spends 6 1/2 hours working for every hour of the completed audiobook.
b. Zhen completes 6 1/2 audiobooks in an hour.
c. Zhen spends 6 1/2 hours working per audiobook.
It means that Zhen needs 6 1/2 working hours to record 1 hour of the audiobook. Zhen needs to work more than one hour to record one hour of the audiobook, because besides recording, he also needs to research and edit.