Question

$\frac{8a+2b}{8a-2b}=\frac{7}{1}$, Find the value of b : a.

Answer 1

$\frac{8a+2b}{8a-2b}=\frac{7}{1}$

$\frac{8a+2b+8a-2b}{8a+2b-8a+2b}=\frac{7+1}{7-1}$ [Applying componendo and dividendo] (1 Mark)

$\frac{16a}{4b}=\frac{8}{6}$ (0.5 Marks)

$4\frac{a}{b}=\frac{4}{3}$ (0.5 Marks)

$\frac{a}{b}=\frac{1}{3}$ (0.5 Marks)

$\frac{b}{a}=\frac{3}{1}$ (Applying invertendo) (0.5 Marks)

Hence b : a = 3 : 1