{2x-y=3 |*1 x+y=3 |*(-2)
{2x-y=3, -2x-2y=-6; 2x-y=3 + -2x-2y=-6 --------------- -3y=3 y=3:(-3) y=-1 {y=-1, x+y=3; {y=-1, x-1=3; {y=-1, x=3+1; {y=-1, x=4. Ответ: ( 4;-1)