Filling Wine in Barrels

         A friend of mine in London has a very nice cellar. He has two large barrels in the cellar. The larger barrel is mostly empty. But the smaller barrel is only 5/6^th full of wine while it can hold 536 litres.

         Supposing he empties the smaller barrel and fills the bigger barrel to find that the wine fills only 4/9ths of it, how much wine would the larger barrel hold when full?

Answer:  630 Litres: Let us assume x is the capacity of the second barrel.

Then our equation will be:

5/6 x 336 = 4/9 x X

X = 5 x 336 x 9 / 6x 1x 4 =630