\[\boxed{\text{1256.}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[1)\ \left\{ \begin{matrix} 4x + y = 7\ \ \ \ | \cdot 6 \\ 5x - 6y = 30\ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} 24x + 6y = 42 \\ 5x - 6y = 30\ \ \\ \end{matrix} \right.\ \]
\[2)\ \left\{ \begin{matrix} 2x + 4y = 9\ \ \ \ | \cdot ( - 5) \\ 3x + 20y = 40\ \ \ \ \ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]
\[\left\{ \begin{matrix} - 10x - 20y = - 40 \\ 3x + 20y = 40\ \ \ \ \ \ \ \ \ \\ \end{matrix} \right.\ \]