2011-II-02

Ans: A

\begin{array}{rcl} \frac{2 + a}{a} & = & \frac{2 - x}{x} \\ x (2 + a) & = & a (2 - x) \\ x (2 + a) & = & 2 a - a x \\ x (2 + a) + a x & = & 2 a \\ x (2 + 2 a) & = & 2 a \\ x & = & \frac{2}{2 + 2 a} \\ x & = & \frac{1}{1 + a} \end{array}

2011, HKCEE, Paper 2 Change of Subject