Which part of that is giving you trouble?
I recommend the Variable version. It'd look something like this:
When you finish a quest:
Control Variables: Variable 003 +=1
When you go back to the person, have the last page of the event have the Page Condition of, say, Variable 003 greater than or equal to 10, if there are 10 quests.
The other version involves, say, a 10-layer nest of Conditional Branches, and I don't really recommend it.