As the given lines are:
[tex]\begin{gathered} x+y=7\ldots\ldots\ldots\ldots(1) \\ 2x-3y=-11\ldots\ldots\ldots.(2) \end{gathered}[/tex]To find the system of linear equation:
multiply equation (1)by 3 and then add in equation 2:
[tex]\begin{gathered} 3(x+y)+2x-3y=3(7)-11 \\ 3x+3y+2x-3y=21-11 \\ 5x=10 \\ x=2 \end{gathered}[/tex]Now put the value of x in equation 1:
[tex]\begin{gathered} 2+y=7 \\ y=5 \end{gathered}[/tex]