$\left. \begin{align} & \frac{3}{y}=\frac{5}{10}\to y=\frac{10\times 3}{5}=6 \\ & \frac{\frac{x}{8}=\frac{5}{10}\to x=\frac{8\times 5}{10}=4}{{}} \\ \end{align} \right\}\to x+y=10$