Question

2у+х=40
×-у=4
С помощью способа подстановки

Answer 1

$\left \{ {{2y+x=40} \atop {x-y=4}} \right.$

$\left \{ {{2y+x=40} \atop {x=4+y}} \right.$

$\left \{ {{2y+4+y=40} \atop {x=4+y}} \right.$

$\left \{ {{3y=36} \atop {x=4+y}} \right.$

$\left \{ {{y=12} \atop {x=4+y}} \right.$

$\left \{ {{y=12} \atop {x=16}} \right.$

Ответ: x=16; y=12