\[5x - 2 = a\]
\[5x = a + 2\]
\[x = \frac{a + 2}{5} \Longrightarrow\]
\[\frac{a + 2}{5} > 0\]
\[a + 2 > 0\]
\[a > - 2\]
\[Ответ:при\ a > - 2.\]