Question

{7х+5у=12. {4х+у=18 способом прибавления​

Answer 1

$\left \{ {7x+5y=12} \atop {4x+y=18 |*(-5)}} \right. \\+\left \{ {7x+5y=12} \atop {-20x-5y=-90 }} \right. \\\\-13x=-78\\x=6\\\\7*6+5y=12\\5y=-30\\y=-6$

Ответ: x = 6; y = -6