\[ax - 5a = 10 - 2x\]
\[ax + 2x = 5a + 10\]
\[x(a + 2) = 5 \bullet (a + 2)\]
\[a = - 2 \Longrightarrow x - любое.\]
\[Ответ:a \in ( - \infty;\ - 2) \cup ( - 2;\ + \infty).\]