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: The number of diagonals of a polygon of n sides is given by the formula z=n(n-3)/2. If a polygon has twice as many diagonals as sides, how many sides does it have?

 Option A:  3

 Option B:  5

 Option C:  6

 Option D:  7

 Option E:  8

A: Option B
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Q: Question: A reduction of 25% in the price of oil enables a house wife to obtain 5kgs more for Rs.800, what is the reduced price for kg?

 Option A: 72

 Option B: 27

 Option C: 40

 Option D: 28

 Option E: 20

A: Option C
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Q: Question: If 16% of 40% of a number is 5, then the number is

 Option A: 200

 Option B: 225

 Option C: 78.125

 Option D: 320

 Option E: None of these

A:
Option C
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