Answer:N/A
Explanation:
I need more context to answer this question.
Eva and Jin volunteer on the first day of the month, if they volunteer once a month (assuming this month has 31 days) it would be 31 days until they volunteer again. Now, if Eva volunteers every 6 days and Jin volunteers every two days (this is just an example) on the sixth of the month is when they will volunteer on the same day. If you want a complete answer I would recommend writing the whole question.