Eileen and Sally jogged at the stadium on 1st May. From then on, Eileen jogged every 3 days while Sally jogged every 4 days. when would they meet next?
day # in May for Eileen:
1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31,
day # in May for Sally:
1, 5, 9, 13, 17, ....
What do you think?