India, Dec. 8 -- Puzzles involving speed and distance, like the one involving trains between Delhi and Amritsar, can never be monotonous because of the variety they offer. Each can be different from the previous one, and even similar ones can be made to look different. Take the following puzzle, for instance. You may have dealt with the same mathematical principles in previous puzzles, but I hope my new construction helps it remain a fun experience to solve.

#Puzzle 172.1

A couple planning to attend a wedding in the next town get into a quarrel just before the journey, so they set off in their separate cars. They start off at the same time and drive at the same steady speed, so they can see each other along the journey, occasionally exc...