Please help me with this question and provide work Vatruvious purchased what he thought were 6 barrels of soda, only to find out that one of the barrels contained apple juice. (He loved apple juice!) The barrels held 15 liters, 19 liters, 20 liters, 16 liters, 31 liters, and 18 liters. He sold some of the barrels to Emmett and some to Lucy. Emmett purchased twice as many liters as Lucy did. Being very fond of apple juice Vatruvious kept this barrel for himself. Which barrel (in liters) contained the apple juice? Of course, Vatruvious sold the barrels as he bought them, without taking a drink from any of the barrels, so tasting didn't help him figure this one out. Also, which barrels did Emmett purchase and which did Lucy purchase?

15 L
19 L
20 L
16 L
31 L
18 L

answer choices: Lucy, Vatruvious kept this one, Emmett