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.
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Question: Problem: a man ' s speed with the current is 18 km / hr and the speed of the current is 2.5 km / hr. the man ' s speed against the current is ?
Options: a. 10, b. 18, c. 50, d. 30, e. 40

Answer: b


Question: Problem: a 270 metres long bullet train running at the speed of 120 kmph crosses another bullet train running in opposite direction at the speed of 80 kmph in 9 seconds. what is the length of the other bullet train ?
Options: a. 226, b. 230, c. 430, d. 310, e. 260

Answer: b


Question: Problem: a ship 77 km from the shore, springs a leak which admits to 9 / 4 tonnes of water in 11 / 2 minutes. 92 tonnes of water would sink it. but the pumps can throw out 12 tonnes of water per hour. find the average rate of sailing so that the ship may just reach the shore as it begins to sink.
Options: a. 10.5, b. 11, c. 12, d. 13, e. 15

Answer:
a