Respuesta :

[tex]\left \{ {{4x - 4y = -12} \atop {x + 4y = -18}} \right. <=>\left \{ {{5x=-30} \atop {x + 4y = -18} \right. <=> \left \{ {x=-6} \atop {y=-3} \right.[/tex]

ok done. Thank to me :>