[x-y=4, 2x + y = 2; 4x+2y=1, -2x+y=3. 11x-2y=14, 33x+y=70.

\[\begin{cases}x - y = 4 \\2x + y = 2\end{cases}\]

\[\begin{cases}4x + 2y = 1 \\-2x + y = 3\end{cases}\]

\[\begin{cases}11x - 2y = 14 \\33x + y = 70\end{cases}\]