Peter arrives at 9:50
Closing time is 10:30
9:50 = 9*60+50 minutes
= 540 + 50
= 590 minutes
10:30 = 10*60 + 30 minutes
= 600+30
= 630 minutes
Time long before closing time = 630-590
= 40 minutes
Therefore, Peter reached 40 minutes before closing time.
