Detailed Instructions: 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.
Q: Problem: 2 pipes can separately fill a tank in 20 hrs and 30 hrs respectively. both the pipes are opened to fillthe tank, a leak develops in the tank through which one - third of water supplied by both the pipes goes out. what is the total time taken to fill the tank ?
Options: a. 10 hrs, b. 12 hrs, c. 16 hrs, d. 18 hrs, e. 20 hrs
A:
c