Объяснение:

[tex]\left \{ {{x+y=7} \atop {9x-2y=1}} \right. \ \ \ \ \ \left \{ {{y=7-x} \atop {9x-2*(7-x)=1}} \right.\ \ \ \ \left \{ {{y=7-x} \atop {9x-14+2x=1}} \right.\ \ \ \ \left \{ {{y=7-x} \atop {11x=15\ |:11}}\ \ \ \ \left \{ {{y=5\frac{7}{11} } \atop {x=\frac{15}{11} =1\frac{4}{11} }} \right. \right. .[/tex]

Ответ: (1⁴/₁₁;5⁷/₁₁).