5. A brother and a younger brother set off from home to a school 2000 meters away at the same time. The brother walks 60 meters per minute, and the younger brother walks 50 meters per minute. After walking for 10 minutes, the brother realizes he forgot to bring his math correction book, so he runs back home at a speed of 100 meters per minute. After getting home, the brother spent 2 minutes finding the correction book, and then ran to the school at a speed of 150 meters per minute. Starting from when the brother sets off from home for the second time, it will take $\qquad$ minutes for the brother to catch up with the younger brother.
5. 【Answer】9