Is this a homework or certification question? Please forgive me if it is not, but it sounds a lot like a question from the MCTS.
Anyway, the first question is do you have log backups and is it in full recovery mode? If so, attempt to do a backup of the remaining log tail, then restore the full, restore the 8:00PM differential, and then restore the log backups.
If not, restore the full and the 8:00pm differential and accept that you have lost all changes from 8:00 - 9:00. Then seriously consider if you can afford that kind of data loss and consider if you need to implement log backups.
A differential backup includes everything since the last Full backup (that didn't use the COPY_ONLY option). Therefore, any restore sequence will only require at most one differential backup.
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