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.
--------
Question: Problem: a 10000 liter tank, half - full of water is being filled from a pipe with a flow rate of 1 kiloliter every 2 minutes. at the same time, the tank is losing water from two drains at a rate of 1 kiloliter every 4 minutes and every 6 minutes. how many minutes does it take to fill the tank completely ?
Options: a. 8, b. 12, c. 18, d. 24, e. 60

Answer: e


Question: Problem: how many 4 - digit numbers that do not contain the digits 2, 3, 4, 5, 6, or 7 are there ?
Options: a. 168, b. 176, c. 184, d. 192, e. 200

Answer: d


Question: Problem: $ 100 is divided amongst a, b and c so that a may get 1 / 4 as much as b and c together, b may get 3 / 5 as much as a and c together, then the share of a is
Options: a. $ 15, b. $ 20, c. $ 25, d. $ 18, e. $ 30

Answer:
b