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.
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Question: Question: In a certain school, the ratio of boys to girls is 5 to 13. If there are 160 more girls than boys, how many boys are there?

 Option A: 100

 Option B: 36

 Option C: 45

 Option D: 72

 Option E: 117

Answer: Option A


Question: Question: If the operation ∆ is defined by a ∆ b = (b - a)^2/a^2 for all numbers a and b, and a ≠ 0, then what is the result when we evaluate this expression: (-5) ∆ (5 ∆ −5) ?

 Option A: 49/9

 Option B: 49/16

 Option C: 81/16

 Option D: 81/25

 Option E: 100/81

Answer: Option D


Question: Question: Two pipes can fill the cistern in 10hr and 12 hr respectively, while the third empty it in 15hr. If all pipes are opened simultaneously, then the cistern will be filled in

 Option A: 7.5 hr

 Option B: 8 hr

 Option C: 8.57 hr

 Option D: 10 hr

 Option E: None of these

Answer:
Option C