The above picture represents the drums stocked with wine at the shop. Each number represents the quantity in the same unit.
At the end of the day, the last remaining drum is retained by the store owner since it contains red wine, while the rest contained white. While going through the sales record of the day, the owner realized the following, "The first buyer received three times the quantity as much as the second while the third received twice as much as the second."
Can you identify which drum contained the red wine?
As a bonus you can also mention the quantity purchased by each buyer.
Addendum : To make the solution unique "The number of drums sold to each were the same".
Note : I am more interested in the methodology used to arrive at the solution. Brute force may help, but the problem should be solvable using only pencil and paper. Derived from a century old puzzle.