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: 30 pens and 75 pencils were purchased for 750. if the average price of a pencil was 2.00, find the average price of a pen.
Options: a. 20, b. 11, c. 12, d. 13, e. 14
[EX A]: a

[EX Q]: Problem: income and expenditure of a person are in the ratio 7: 6. if the income of the person is rs. 14000, then find his savings ?
Options: a. 500, b. 1000, c. 1500, d. 2000, e. 2500
[EX A]: d

[EX Q]: Problem: the average age of 15 students of a class is 15 years. out of these, the average age of 8 students is 14 years and that of the other 6 students is 16 years, the age of the 15 th student is
Options: a. 17, b. 12, c. 13, d. 14, e. 15
[EX A]:
a