Question

Решите уравнения, даю 20 баллов​

Answer 1

1)

$\left \{ {{3x+2y=42} \atop {2x+4y=60}} \right. \\\left \{ {{3x+2y=42} \atop {x+2y=30}} \right. \\3x+2y-x-2y=42-30\\2x=12\\x=6\\6+2y=30\\2y=24\\y=12\\\left \{ {{x=6} \atop {y=12}} \right.$

2)

$\left \{ {{3x-y=5} \atop {2x+y=5}} \right. \\3x-y+2x+y=5+5\\5x=10\\x=2\\4+y=5\\y=1\\\left \{ {{x=2} \atop {y=1}} \right.$