Question

{7x-15y=-129
-3x-11y=3

Answer 1

$\left \{ {{7x-15y=-129|*3} \atop {-3x-11y=3|*7}} \right. \Longrightarrow \left \{ {{21x-45y=-387} \atop {-21x-77y=21}} \right.$

$+\left \{ {{21x-45y=-387} \atop {-21x-77y=21}} \right. \\\\---------\\-122y=-366\\y=3\\\\-21x-77*3=21\\-21x-231=21\\-21x=252\\x=-12$

Ответ: (-12; 3)