Okay, today is ratio/unit conversion day it seems like for Brainly.
You can solve this by looking at:
80beats/1min = 1,000,000/x
Then, use cross multiplication to get x.  This will be in minutes!  You will need to convert this to hours and then to days to arrive at the answer.
I hope this helps!
Edit: 8.68 days!  Also the amount of days I have until I can see my kids for a few hours!