Question

Решительно систему уравнений

Answer 1

$\left \{ {{2x+5y=-7} \atop {3x-y=15}} \right. \left \{ {{2x+5y=-7} \atop {15x-5y=75}} \right. \; +\; \left \{ {{2x+5y=-7} \atop {17x=68}} \right. \; \left \{ {{2x+5y=-7} \atop {x=4}} \right. \; \left \{ {{5y=-7-8} \atop {x=4}} \right. \; \left \{ {{y=-15} \atop {x=4}} \right.$