$\left \{ {{3x=-2(y-5)} \atop {5x+5=-3y}} \right.$
$⇔\left \{ {{3x=-2y+10} \atop {5x+3y=-5}} \right.$
$⇔\left \{ {{3x+2y=10} \atop {5x+3y=-5}} \right.$
$⇔\left \{ {{9x+6y=30} \atop {10x+6y=-10}} \right.$
$⇔\left \{ {{-x=40} \atop {3x+2y=10}} \right.$
$⇔\left \{ {{x=-40} \atop {3.(-40)+2y=10}} \right.$
$⇔\left \{ {{x=-40} \atop {-120+2y=10}} \right.$
$⇔\left \{ {{x=-40} \atop {y=130}} \right.$
$⇔\left \{ {{x=-40} \atop {y=65}} \right.$
#Mình dùng p² cộng đại số nha
