[tex]x-y=11 \\
2x+y=19 \\ \\
\hbox{solve the 1st equation for x:} \\
x-y=11 \\
x=11+y \\ \\
\hbox{substitute 11+y for x in the 2nd equation:} \\
2(11+y)+y=19 \\
22+2y+y=19 \\
22+3y=19 \ \ \ |-22 \\
3y=-3 \ \ \ |\div 3 \\
y=-1 \\ \\ x=11+y=11-1=10 \\ \\
(x,y)=(10,-1)[/tex]
