I walk from home to school in 30 minutes, while my brother takes 40 minutes. How many minutes will it take for me to catch up with my brother if he left the house 5 minutes before me?
If I had left 10 minutes later, I would have caught up with my brother in 30 minutes (by the school). Since 5 is half of 10, I will catch up with him twice as fast.

## Answer

In 15 minutes.