\[а)\ \left\{ \begin{matrix}
y = - x + 2 \\
y = x\ \ \ \ \ \ \ \ \ \ \\
\end{matrix} \right.\ \]
\[б)\ \left\{ \begin{matrix}
y = 2 - 2x \\
y = 4\ \ \ \ \ \ \ \ \ \ \\
\end{matrix} \right.\ \]
\[в)\ \left\{ \begin{matrix}
y = - \frac{2}{3}x - 2 \\
y = - \frac{2}{3}x + 2 \\
\end{matrix} \right.\ \]