Answer: 12 minutes.
Step-by-step explanation: For two people, it takes an hour to paint a fence. With ten people, however, it takes very little time to paint a fence. 10 people are 5 times more people than when you have only 2. It would only take 12 minutes because it takes 5 times less time with 10 people than with only two.
Let me know if this is right! :)