[tex]\displaystyle \left \{ {{u-2t=5} \atop {5u-6t=33}} \right. \\\\-5(-2t+u)+(-6t+5u)=-5*5+33\\4t=8\\t=2\\-2t+u=5\\u=9\\(t,u)=(2,9)[/tex]

[tex]\left \{ {{u-2t=5} | *(-3)\atop {5u-6t=33}} \right.\\+ \left \{ {{-3u+6t=-15}\atop {5u-6t=33}} \right.\\\\-3u+6t+5u-6t=-15+33\\2u=18\\u=18/2\\u=9\\\\9-2t=5\\2t=9-5\\2t=4\\t=2\\[/tex]

Ответ:

[tex]\left \{ {{u=9} \atop {t=2}} \right.[/tex]