Definition: 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.
Input: Problem: gopi gives rs. 90 plus one turban as salary to his servant for one year. the servant leaves after 9 months and receives rs. 60 and the turban. find the price of the turban.
Options: a. 27, b. 30, c. 29, d. 10, e. 11
Output:
b