Question

Срочно!!!Решите линейное уравнение!!!

Answer 1

$\left \{ {{3x+4y=55} \atop {7x-y=56}} \right. \\\left \{ {{3x+4y=55} \atop {y=-56+7x} \right. \\3x+4(-56+7x)=55\\x=9\\y=-56+7*9\\y=7\\(x,y)=(9,7)\\\left \{ {{3*9+4*7=55} \atop {7*9-7=56}} \right.\\\left \{ {{55=55} \atop {56=56}} \right. \\(x,y)=(9,7)$