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: a tyre has two punctures. the first puncture alone would have made the tyre flat in 9 minutes and the second alone would have done it in 6 minutes. if air leaks out at a constant rate, how long does it take both the punctures together to make it flat ?
Options: a. 315 min, b. 325 min, c. 335 min, d. 345 min, e. none of these
Output:
c