[tex]\displaystyle \left \{ {{7x-y=-42} \atop {4x+7y=29}} \right.\\ \\\left \{ {{y=42+7x} \atop {4x+7y=29}} \right. \\\\4x+7(42+7x)=29\\x=-5\\y=42+7(-5)\\y=7\\(x,y)=(-5,7)[/tex]

Ответ:

(-5;7)

Объяснение: