The clock shows 3:45, 15 minutes slow, you say? That would mean the actual time is 3:45 + 00:15, or 3:60 in time notation. But 3:60 doesn't make sense. Let's redo that by adding the minutes... 3 hours plus 15 minutes becomes 60+ 60 is 4 and add the remaining 5 minutes to be ... 4:05