Решите систему уравнений x/3=-y/4 x+y=5

[latex] \left \{ {{ \frac{x}{3}=- \frac{y}{4} } \atop {x+y=5}} \right. [/latex] [latex] \left \{ {{ \frac{x}{3}=- \frac{y}{4} } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{ \frac{5-y}{3}=- \frac{y}{4} } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{ \frac{5-y}{3}+\frac{y}{4}=0 } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{ \frac{4(5-y)}{12}+\frac{3y}{12}=0 } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{ 4(5-y)+3y=0 } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{20-4y+3y=0 } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{20-y=0 } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{y=20 } \atop {x=5-y}} \right. [/latex] [latex] \left \{ {{y=20 } \atop {x=5-20}} \right. [/latex] [latex] \left \{ {{y=20 } \atop {x=-15}} \right. [/latex] ответ: (-15; 20)

[latex] \frac{x}{3} =- \frac{y}{4} [/latex] [latex]x+y=5      x=5-y[/latex] [latex] \frac{5-y}{3} =- \frac{y}{4} [/latex] [latex]20-4y=-3y[/latex] [latex]-4y+3y=-20[/latex] [latex]y=20[/latex] [latex]x=5-20[/latex] [latex]x=-15[/latex] ответ([latex]-15;20[/latex])