Ответ:
\left \{ {{y=7-3x} \atop {2y-5x=3}} \right.\\\\ 2(7-3x)-5x=3\\\\14-6x-5x=3\\\\-11x=-11\\\\11x=11\\\\x=\frac{11}{11}\\\\ x=1\\\\\\y=7-3\times1\\\\y=7-3\\\\y=4" alt="\left \{ {{3x+y=7} \atop {2y-5x=3}} \right.=>\left \{ {{y=7-3x} \atop {2y-5x=3}} \right.\\\\ 2(7-3x)-5x=3\\\\14-6x-5x=3\\\\-11x=-11\\\\11x=11\\\\x=\frac{11}{11}\\\\ x=1\\\\\\y=7-3\times1\\\\y=7-3\\\\y=4" align="absmiddle" class="latex-formula">