Системы уравнений
247.
\[\left\{ \begin{array}{l}
\frac{{x - y}}{5} - \frac{{x + y}}{2} = 10 \hfill \\
\frac{x}{5} + \frac{y}{2} = 10 \hfill \\
\end{array} \right.\]
248.
\[\left\{ \begin{array}{l}
\frac{{x + y}}{2} + \frac{{x - y}}{3} = 6 \hfill \\
\frac{{x + y}}{4} - \frac{{x - y}}{3} = 0 \hfill \\
\end{array} \right.\]