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.

[EX Q]: Problem: the ratio of the present age of viju to that of aju is 7: 2. 4 years from now, the ratio of the ages of viju to aju will be 5: 2. what was viju age 5 years ago ? ( rbi assistant 2015 )
Options: a. 24, b. 18, c. 12, d. 16, e. 13
[EX A]: d

[EX Q]: Problem: 3 ltr of water is added with 9 ltr of a solution containing 57 % of alcohol in the water. the % of alcohol in the new mixture is ?
Options: a. 41.5 %, b. 42.75 %, c. 43 %, d. 45 %, e. 45.75 %
[EX A]: b

[EX Q]: Problem: a technician makes a round - trip to and from a certain service center by the same route. if the technician completes the drive to the center and then completes 40 percent of the drive from the center, what percent of the round - trip has the technician completed ?
Options: a. 5 %, b. 70 %, c. 25 %, d. 40 %, e. 55 %
[EX A]:
b