Đáp án:
\(\left\{ \begin{array}{l}
y = 5\\
x = - 2
\end{array} \right.\)
Giải thích các bước giải:
\(\begin{array}{l}
\left\{ \begin{array}{l}
\dfrac{x}{2} = - \dfrac{y}{5}\\
x - y = - 7
\end{array} \right.\\
\to \left\{ \begin{array}{l}
x = - \dfrac{2}{5}y\\
- \dfrac{2}{5}y - y = - 7
\end{array} \right.\\
\to \left\{ \begin{array}{l}
- \dfrac{7}{5}y = - 7\\
x = - \dfrac{2}{5}y
\end{array} \right.\\
\to \left\{ \begin{array}{l}
y = 5\\
x = - 2
\end{array} \right.
\end{array}\)
