Answer :
3/4 of an hour is 45 minutes. So they spent 3 hours and 45 minutes at the beach. They arrived at 10:30 so just add 3 hours and 45 minutes to their arrival time and you get 2:15pm. They left at 2:15pm
10:30+3:45=14:15
14:15=2:15
10:30+3:45=14:15
14:15=2:15
