I'll show you two ways.
By substitution:
[tex]x+3y=11\\
2x-y=1\\\\
x=11-3y\\
2x-y=1\\\\
2(11-3y)-y=1\\
22-6y-y=1\\
-7y=-21\\
y=3\\\\
x=11-3\cdot3\\
x=11-9\\
x=2\\\\
\boxed{(x,y)=\left(2,3\right)}[/tex]
By elimination:
[tex]x+3y=11\\ 2x-y=1|\cdot 3\\\\
x+3y=11\\
\underline{6x-3y=3}\\
7x=14\\
x=2\\\\ 2+3y=11\\
3y=9\\ y=3\\\\
\boxed{(x,y)=\left(2,3\right)}[/tex]