Fairly Distributed Assets

What was dilemma? 

We have to make number of each barrel type divisible by 3.

1.Two half-full barrels are poured into 1 empty barrel. So we left with 8 full, 5 half-empty & 8 empty barrels.

2.Again transfer two half-fulled barrels into 1 empty. Now we have 9 full, 3 half-empty & 9 empty barrels.

Now it can be evenly divided as 3 full, 1 half-empty & 3 empty barrels (hence wine) among 3 sons.