Question

An ‘A' train leaves a subway station every 12 minutes. An ‘E' train leaves every 9minutes. If both trains just left the station on parallel tracks, when will both leave the station together again? A. In 108 minutes B. In 36 minutes C. In 72 minutes D. In 24 minutes

Answer 1

The answer is B.
The smallest multiple (least common denominator) that both 9 and 12 share is 36.