You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Q: Question: By selling 12 toffees for a rupee, a man loses 20%. How many for a rupee should be sell to get a gain of 20%?

 Option A: 5

 Option B: 8

 Option C: 10

 Option D: 15

 Option E: 20

A: Option B
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Q: Question: An inspector rejects 15% of the meters as defective. How many will he examine to reject 15?

 Option A: A

 Option B: B

 Option C: C

 Option D: D

 Option E: E

A: Option A
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Q: Question: Chang Li has pet cockroaches that multiply at the same rate every week.
The first week he had 5, the next week he had 10, the second week he had 20, and the fourth week he had 80. How many did he have on week 3?

 Option A: 30

 Option B: 25

 Option C: 40

 Option D: 60

 Option E: 50

A:
Option C
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