Riddles, brain puzzles and mathematical problems

[Bridge]

Can't wait BAndrew. Depending on how much time it will take you might consider finding a puzzle online to keep things going, and then you can post your custom puzzle when it's ready.

Great idea. Here goes then:

Restless Dog:

A person is returning home with his dog after a walk in the park. The man is walking at a constant speed of 4 km/h. Because the dog is very restless, 8 km before arriving the dog leaves the man and runs away to reach home. The dog runs at a constant speed of 10 km/h. When the dog arrives at the house he sees that the door is locked and changes direction to go to his boss. When the dog reaches the man it changes again its direction to the house. The same process is repeated until the man finally reaches home and unlocks the door.

Question: How far will the dog have travelled since it run away from his master for the first time?

20km?