There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?
When a clock is observed, the hour hand is at a minute mark and the minutes hand is six minutes ahead of it.
When the clock is observed again after some time, the hour hand is precisely on a different minute mark and the minute hand is seven minutes ahead of it.
Can you calculate how much time has elapsed between the two observations?