\[(a - 3)x \leq a - 3\]
\[a = 3,\ \]
\[0 \cdot x \leq 0 \Longrightarrow \ ( - \infty;\ + \infty)\]
\[a < 3,\ \ x \geq 1\]
\[a > 3,\ \ x \leq 1.\]