[tex] \left \{ {{x+4y=8\ \ | multiply\ by\ -2} \atop {2x-5y=29\ \ \ \ \ \ \ \ \ \ \ \ \ \ }} \right. \\\\ \left \{ {{-2x-8y=-16} \atop {2x-5y=29}} \right. \\+-----\\ add\ both\ equations\\\\
-13y=13\ \ \ | divide\ by \ -13\\\\
y=-1\\\\
x=8-4y=8-4(-1)=8+4=12\\\\
x=12[/tex]
