\(\frac{p + q}{a(p - q)}\)
\(\frac{p - q}{a(p + q)}\)
\(\frac{p - q}{apq}\)
\(\frac{pq}{a(p - q)}\)
Correct answer is B
\(\frac{1 + ax}{1 - ax}\) = \(\frac{p}{q}\) by cross multiplication,
q(1 + ax) = p(1 - ax)
q + qax = p - pax
qax + pax = p - q
∴ x = \(\frac{p - q}{a(p + q)}\)