Question

плиз помогите поставлю 5 балов​

Answer 1

$\displaystyle \left \{ {{x+y=-1} \atop {3x+3y=-2}} \right. \\\\\left \{ {{x=-1-y} \atop {3x+3y=-2}} \right. \\\\3(-1-y)+3y=-2\\\oslash$