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: A and B together can do a work in 3 days. If A alone can do it in 12 days. In how many days can B alone do it?

 Option A: 4

 Option B: 6

 Option C: 8

 Option D: 10

 Option E: 25

A: Option A
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Q: Question: A boat takes 19 hours for travelling downstream from point A to point B and coming back to a point C midway between A and B. If the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph, what is the distance between A and B ?

 Option A: 160 km

 Option B: 180 km

 Option C: 200 km

 Option D: 220 km

 Option E: None

A: Option B
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Q: Question: Walking 6/7 of his usual rate, a boy reaches his school 4 min early. Find his usual time to reach the school?

 Option A: 28 m

 Option B: 20 m

 Option C: 22 m

 Option D: 23 m

 Option E: 24 m

A:
Option E
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