Posted by Terry on Wednesday, October 17, 2012 at 5:01pm.
I would start making a chart,
for Artie, his next shopping days are
5, 10, 15, 20, 25, 30,. . . days after Tuesday
for Tom, his next shopping days are
4, 8, 12, 16, 20, 24,
The first time they meet is the GCF of 4, and 5, or 20 days after Tuesday.
The day of the week is Tuesday + 20mod7, or Tuesday + 6 days, or a Monday