Please do NOT post your answer, but do say if you think you have solved the puzzle and how long it took. Solution on Monday.
Yesterday I decided to walk from my house to my office. The journey is 5 miles long and I walked at a steady 2 miles per hour. When I arrived at the office 40 buses had overtaken me and 50 buses had come from the direction of my office. What was the average speed of the buses?
I have produced an ebook containing 101 of the previous Friday Puzzles! It is called PUZZLED and is available for the Kindle (UK here and USA here) and on the iBookstore (UK here in the USA here). You can try 101 of the puzzles for free here.