{2х+4y-90=0 {x-3y-10=0 решениe

[latex] \left \{ {{2x+4y-90=0} \atop {x-3y-10=0}} \right. \\ \\ \left \{ {{2x+4y-90=0} \atop {2x-6y-20=0}} \right. \\ \\ 4y-(-6y)-90-(-20)=0 \\ 4y+6y-90+20=0 \\ 10y-70=0 \\ 10y=70 \\ y=7 \\ x-3*7-10=0 \\ x-21-10=0 \\ x=31 \\ \\ \left \{ {{x=31} \atop {y=7}} \right. [/latex]