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The riddle of the water tank or the tank issue is one of the content in the book " The nine chapters on mathematical art " one of the oldest books math China, dating back to the period of Zhou Dynasty.

Riddle:
We have a water tank of 48 m3 capacity with two filling pipes and drain .
The first filler pipe open one would take 12 hours to fill the tank .
The second filler pipe open only take six hours to fill the tank.
With fully fueled and the two filling lines closed , the discharge pipe would take eight hours to remove all the water and leave the empty tank.

Question:
If we start from the empty tank and open the three pipes how long it would take to fill the tank?

See the solution to the riddle