The Puzzle: A girl, a boy, and a dog start walking down a road.
They start at the same time, from the same point, in the same direction.
The boy walks at 5 km/h, the girl at 6 km/h.
The dog runs from boy to girl and back again with a constant speed of 10 km/h. The dog does not slow down on the turn.
How far does the dog travel in 1 hour?
It's pretty hard to give up.
If you remove a part of it, you will be left with a bit.
Even if you remove another part, the bit still remains.
Remove one more and it still remains.