Помогите выразить:[latex] \left \{ {{5x+6y=13} \atop {7x+18y+1=0}} \right. [/latex]

[latex] \left \{ {{5x+6y=13|*(-3)} \atop {7x+18y+1=0}} \right. \left \{ {{-15x-18y=-39} \atop {7x+18y=-1}} \right. \left \{ {{-8x=-40} \atop {5x+6y=13}} \right. \left \{ {{x=(-40):(-8)} \atop {5x+6y=13}} \right. [/latex] [latex] \left \{ {{x=5} \atop {5*5+6y=13}} \right. \left \{ {{x=5} \atop {25+6y=13}} \right. \left \{ {{x=5} \atop {6y=13-25}} \right. \left \{ {{x=5} \atop {y=(-12):6}} \right. \left \{ {{x=5} \atop {y=-2}} \right. [/latex]