З (х +4 у) -4 х=2 (2 х + у) , 7 (х-5 у)+6 х=3

\left \{ {{3x+12y-4x-4x-2y=0} \atop{7x-35y-3x-12y-27=0}} \right.\left \{ {{10y-5x=0} \atop{4x-47y-27=0}} \right.\left \{ {{x=2y} \atop{-39y=27}} \right.\left \{ {{y=-\frac{9}{13}} \atop{x=1+\frac{5}{13}}} \right. Ответ-\frac{9}{13}; 1+\frac{5}{13}).