Question 630035
Lets pretend that today is the 7/1. Lets make a table for the next few times George and Martha swam.
George| Martha|
7/6 |7/4 |
7/11|7/7 |
7/16|7/10|
7/21|7/13|
7/26|7/16|
And we'll stop there. If you look at the table, then you can see that 7/16 is on both columns. That means it will take 15 days for them to swim together again.