Решить систему уравнений :а)4х+15у=-42-6х+25у=-32 в)12х-35у=25-8х-15у=-55 

а) [latex]\left \{ {{4x+15y=-42} \atop {-6x+25y=-32}} \right. \Rightarrow \left \{ {{12x+45y=-126} \atop {-12x+50y=-64}} \right. \Rightarrow \left \{ {{95y=-190} \atop {-12x+50y=-64}} \right. \Rightarrow[/latex] [latex]\Rightarrow\left \{ {{y=-2} \atop {12x=-36}} \right. \Rightarrow \left \{ {{y=-2} \atop {x=-3}} \right.[/latex]  в)   [latex] \left \{ {{12x-35y=25} \atop {-8x-15y=-55}} \right. \Rightarrow \left \{ {{24x-70y=50} \atop {-24x-45y=-165}} \right. \Rightarrow \left \{ {{-115y=-115} \atop {-8x-15y=-55}} \right. \Rightarrow [/latex] [latex]\Rightarrow \left \{ {{y=1} \atop {8x=40}} \right. \Rightarrow\left \{ {{y=1} \atop {x=5}} \right.[/latex]