Question

Mark (✓) against the correct answer

If $\frac{x-1}{x+1}=\frac{7}{9},$ then x = ?

(a) 6
(b) 7
(c) 8
(d) 10

Answer 1

$$\begin{gathered} \begin{array}{l}\left(\text{c}\right)8\\ \text{We have:}\\ \frac{x-1}{x+1}=\frac{7}{9}\\ \Rightarrow 9(x-1)=7(x+1)\end{array} \\ \Rightarrow 9x-9=7x+7 \\ \begin{array}{l}\Rightarrow 9x-7x=7+9\\ \Rightarrow 2x=16\\ \Rightarrow x=\frac{\sout{1}{\sout{6}}^8}{{\sout{2}}_1}\\ \Rightarrow x=8\end{array} \end{gathered}$$