you have the misfortune to own an unreliable clock. this one gains exactly 18 mins every hour. it is now showing 1pm, and you know that it was correct at midnight when you set it. The clock stopped 12 hours ago, what time is it now?
Yes it gains 18 mins per hour, which is 18 X 13 hours up to when the clock stopped. That's 234 Mins = 3 hours 9 mins. Take that away from 1 pm when the clock stopped and the real time was 9 .51 am when the clock stopped. But that was 12 hours ago so the time is now plus 12 hours. That's 9.51 pm.