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: In an electric circuit, two resistors with resistances x and y are connected in parallel. If R is the combined resistance of these two resistors, then the reciprocal of R is equal to the sum of the reciprocals of x and y. What is R if x is 5 Ohms and y is 7 Ohms?

 Option A: 3/5

 Option B: 1/7

 Option C: 12/35

 Option D: 31/12

 Option E: 35/12

A: Option E
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Q: Question: In 120 m race, A covers the distance in 36 seconds and B in 45 seconds. In this race A beats B by:

 Option A: 24 m

 Option B: 25 m

 Option C: 22.5 m

 Option D: 9 m

 Option E: 12 m

A: Option A
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Q: Question: The C.P of 10 pens is equal to the S.P of 12 pens. Find his gain % or loss%?

 Option A: 6 2/5%

 Option B: 6 2/7%

 Option C: 6 2/3%

 Option D: 6 5/3%

 Option E: 6 7/3%

A:
Option C
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