Why? (I'm not assuming the following, but I do need it to explain) Let's say it's the same day where two people, A and B, are facing each other going along the same path and A winds up where B's at and B winds up where A is at. At some point along the way, A and B pass each other (after 9 AM which is a given in the problem).

Based on the above explanation it's evident that Nola must pass the same point (after 9 AM) at the same time on Monday and Tuesday.