Given below are two quantities named A and B. Based on the given information, you have to determine the relationship between the two quantities. You should use the given data and your knowledge of Mathematics to choose between the possible answers.

Quantity A: A can contain a mixture of two liquids A and B in the ratio 3 : 5. When 12 liters of mixture is drawn out and the same quantity of liquid B is filled in the can, the ratio of A and B becomes 1 : 3. How many liters of liquid A were contained by the can initially? 

Quantity B: 9 liters