3) $\begin{array}{l}x-y=11 \\ 2 x+y=19\end{array}$

Step 1 ：Given the system of linear equations: \(x - y = 11\) and \(2x + y = 19\)

Step 2 ：We can solve this system by using the elimination method. By adding the two equations, we can eliminate y.

Step 3 ：Adding the two equations gives us \(3x = 30\).

Step 4 ：Solving for x, we get \(x = 10\).

Step 5 ：Substituting \(x = 10\) into the first equation \(x - y = 11\), we can solve for y.

Step 6 ：Solving for y, we get \(y = -1\).

Step 7 ：Final Answer: The solution to the system of equations is \(\boxed{x = 10}\) and \(\boxed{y = -1}\).