Make x the subject of the relation (frac{1 + ax}{1 – ax}) = (frac{p}{q})

A.
(frac{p + q}{a(p – q)}) 
B.
(frac{p – q}{a(p + q)}) 
C.
(frac{p – q}{apq}) 
D.
(frac{pq}{a(p – q)})
Correct Answer: Option B
Explanation
(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)})