Question

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

Answer 1

200х+20у=640 -40х-20у=-160 160х=480 Х=3 У=2

Answer 2

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