<PRE><B>Question 840496</B>
fill up the 50 Liter container
empty that into the 40 which will leave 10 L in the 50L
pour those ten liters into the 100L
pour the 40 liters back into the 50L 
fill up the 50 liter from the stream  
fill up the 40L from the 50 again leaving 10L in the 50 
pour those 10 into the 100L . Now you have 20 liters in the 100L
pour the 40 from the 40L into the 50. fill up the 50L from the stream
pour those 50L into the 100L 
Now you have 70L in the 100L and the other two (40L and 50L ) are empty
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