We can solve this question using matching operations and a bit of number sense

Given:
Quantity A: \(x\)
Quantity B: \(\frac{1}{x}\)

Subtract \(\frac{1}{x}\) from both quantities to get:
Quantity A: \(x - \frac{1}{x}\)
Quantity B: \(0\)

Find common denominator to get:
Quantity A: \(\frac{x^2}{x} - \frac{1}{x}\)
Quantity B: \(0\)

Combine fractions to get:
Quantity A: \(\frac{x^2-1}{x}\)
Quantity B: \(0\)

Here comes the number sense part:
If \(-1 < x < 0\), then \(0<x^2<1\), which means \(x^2-1\) is NEGATIVE

It's also true that \(x\) is NEGATIVE

Since NEGATIVE/NEGATIVE = POSITIVE, we can be certain that \(\frac{x^2-1}{x}\) = some positive number

So, we get:
Quantity A: some positive number
Quantity B: \(0\)

Answer: A

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