I am usually pretty good with rate problems, but I can't figure this one out.

Problem:

On the 24-mile trip to school, Brandon sauntered at a leisurely pace. Thus, he had to double his speed on the way back to complete the trip in 9 hours. How fast did he travel in each direction, and what were the two times?

(I don't simply want the answer. I want to know how to do it.)

Thank you