Jack plays on a basketball team after school every third day of the month. He babysits his younger brother after school every seventh day of the month. How many times during a 30 day mark if any will jack have a conflict between basketball and babysitting? Explain

Jack will have exactly 1 conflict per month. An easy way to do this is to visualize what he has to do each month.

Basketball:

3, 6, 9, 12, 15, 18, 21, 24, 27, 30

Babysits:

7, 14, 21, 28

Looking above, you can see that only one number is the same, which means there is only one conflict in a 30 day period.