\[\boxed{\text{986\ (986).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[2x - 3y = - 6\ \ \ \ \ и\ \ \ \ \]
\[\ 4x + y = a;\ \ \ \ y = 0\]
\[2x - 3 \cdot 0 = - 6\]
\[2x = - 6\]
\[x = - 3.\]
\[4x + y = a\text{\ \ }\]
\[4 \cdot ( - 3) + 0 = a \Longrightarrow \ \ a = - 12\]
\[Ответ:a = - 12.\]