Given the task definition and input, reply with output. In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: a bucket contains 2 mixtures a and b in the ratio 3 : 2 . if 5 liters of the mixture is replaced by 5 liters of liquid b , then the ratio of the two liquids becomes 3 : 5 . how much of the liquid a was there in the bucket ?
Options: a ) 8 liters , b ) 10 liters , c ) 12 liters , d ) 15 liters , e ) 18 liters
a