Q: Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.
Problem: a jar contains a mixture of ab in the ratio 3: 2. when 20 l of mixture is replaced with liquid b, ratio becomes 2: 3. how many liters of liquid a was present in mixture initially.
Options: a. 12, b. 15, c. 16, d. 20, e. 36
A:
e