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: at what rate percent per annum will a sum of money double in 6 years.
Options: a. 12.5 %, b. 13.5 %, c. 11.5 %, d. 14.5 %, e. 16.6 %

Answer: e


Question: Problem: the product of two positive integers is 675 and their difference is 2. what is the bigger number ?
Options: a. 21, b. 23, c. 25, d. 27, e. 29

Answer: d


Question: Problem: together, 15 type a machines and 7 type b machines can complete a certain job in 4 hours. together 8 type b machines and 15 type c machines can complete the same job in 11 hours. how many w hours would it take one type a machine, one type b machine, and one type c machine working together to complete the job ( assuming constant rates for each machine. ?
Options: a. 22 hours, b. 30 hours, c. 44 hours, d. 60 hours, e. it can not be determined from the information above.

Answer:
c