What is 10:30-8:10
I assume you want to calculate the time elapsed between 10:30-8:10. If that is the case, you should always specify whether it is AM or PM. At any rate, it doesn't matter: I'm going to assume that it is 10:30AM to 8:10PM = 9 hours and 40 minutes. If that is not the case, then specify it correctly next time.
