Respuesta :
Answer:
The 21st day
Step-by-step explanation:
If we mark the days, they will clash on the 21st day.
[tex]3*7=21[/tex]
Hope this helped. Have a nice day! Please mark brainliest!
Answer:
if i think u are talking about when these will over lap then they will over lap on the 21st day
Step-by-step explanation: