If $$\frac{{2x - y}}{{x + 2y}} = \frac{1}{2}{\text{,}}$$   then value of $$\frac{{3x - y}}{{3x + y}}\,{\text{is?}}$$

$$\eqalign{ & \frac{{2x - y}}{{x + 2y}}\, \times \frac{1}{2}\left( {{\text{Cross multiply}}} \right) \cr & \Rightarrow 4x - 2y = x + 2y \cr & \Rightarrow 3x = 4y \cr & \Rightarrow x:y = 4:3 \cr & \therefore \frac{{3x - y}}{{3x + y}}{\text{ }} \cr & {\text{ = }}\frac{{3 \times 4 - 3}}{{3 \times 4 + 3}} \cr & {\text{ = }}\frac{{12 - 3}}{{12 + 3}} \cr & {\text{ = }}\frac{9}{{15}}{\text{ }} \cr & {\text{ = }}\frac{3}{5} \cr} $$