\(\begin{array}{l} \left\{ \begin{array}{l} \dfrac{x}{2} = - \dfrac{y}{5}\\ x - y = - 7 \end{array} \right.\\ \to \left\{ \begin{array}{l} x = - \dfrac{2}{5}y\\ - \dfrac{2}{5}y - y = - 7 \end{array} \right.\\ \to \left\{ \begin{array}{l} - \dfrac{7}{5}y = - 7\\ x = - \dfrac{2}{5}y \end{array} \right.\\ \to \left\{ \begin{array}{l} y = 5\\ x = - 2 \end{array} \right. \end{array}\)
