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: Patrick purchased 80 pencils and sold them at a loss equal to the selling price of 16 pencils. The cost of 80 pencils is how many times the selling price of 80 pencils?

 Option A:  0.75

 Option B:  1.2

 Option C:  1.8

 Option D:  2.4

 Option E:  4.25
[A]: Option B


[Q]: 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
[A]: Option D


[Q]: Question: A man can row upstream at 25 kmph and downstream at 45 kmph, and then find the speed of the man in still water?

 Option A: 11

 Option B: 77

 Option C: 30

 Option D: 88

 Option E: 35
[A]:
Option E