200х+20у=640 20х+10у=80 Решите,пожалуйста!

$\left \{ {{200x+20y=640} \atop {20x+10y=80}} \right.$
$\left \{ {{20x+2y=64} \atop {20x+10y=80}} \right.$
$\left \{ {{20x+2y=64} \atop {20x+10y-(20x+2y))=80-64}} \right.$
$\left \{ {{20x+2y=64} \atop {20x+10y-20x-2y=16}} \right.$
$\left \{ {{20x+2y=64} \atop {8y=16}} \right.$
$\left \{ {{20x+4=64} \atop {y=2}} \right.$
$\left \{ {{20x=60} \atop {y=2} \right.$
$\left \{ {{x=3} \atop {y=2}} \right.$
Ответ: (3;2).