To solve the system
[tex]\begin{gathered} x+2y=13 \\ -x+y=5 \end{gathered}[/tex]we add the two equations to get:
[tex]\begin{gathered} x+2y=13 \\ -x+y=5 \\ --------------_{} \\ 0+3y=18 \end{gathered}[/tex]Dividing both sides by 3 gives
[tex]y=6[/tex]with the value of y in hand, we now put it in -x + y = 5 to get
[tex]-x+6=5[/tex]subtracting 6 from both sides gives
[tex]-x=-1[/tex][tex]x=1[/tex]Hence, the solution to the system is
[tex]\begin{gathered} x=1 \\ y=6. \end{gathered}[/tex]