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: a man spends 2 / 5 of his salary on house rent, 3 / 10 of his salary on food and 1 / 8 of his salary on convenience he has rs. 1400 left with him, find his expenditure on food and conveyance.
Options: a. 1000, b. 3000, c. 4000, d. 2000, e. 5000

A: a
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Q: Problem: the price of a certain painting increased by 30 % during the first year and decreased by 15 % during the second year. the price of the painting at the end of the 2 - year period was what percent of the original price ?
Options: a. 102 %, b. 105 %, c. 110.5 %, d. 112.5 %, e. 100 %

A: c
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Q: Problem: a man swims downstream 60 km and upstream 100 km taking 10 hours each time, what is the speed of the man in still water ?
Options: a. 24, b. 42, c. 6, d. 8, e. 12

A:
d
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