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: 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
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Q: Question: What is the area of an equilateral triangle whose one side length is 80?

 Option A: 800√3

 Option B: 1000√3

 Option C: 1200√3

 Option D: 1400√3

 Option E: 1600√3

A: Option E
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Q: Question: One hour after Matthew started waking from e to y, a distance of 45km, Johnny started walking along the same road from y to e. Matthew's walking rate was 3 km per hour and Johnny's was 4km per hour, how many km had Johnny walked when they met?

 Option A: 24

 Option B: 23

 Option C: 22

 Option D: 21

 Option E: 19.5

A:
Option A
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