Question

$13x + 7y = 141 \\ 5y - 3 = 7x$
это уравнение с 2 переменными
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Answer 1

$\displaystyle\bf\\\left \{ {{13x+7y=141} \atop {5y-3=7x}} \right. \\\\\\\left \{ {{13x+7y=141 \ |\cdot 5} \atop {-7x+5y=3 \ |\cdot(-7)}} \right. \\\\\\+\left \{ {{65x+35y=705} \atop {49x-35y=-21}} \right. \\------------\\114x=684\\\\x=684:114=6\\\\5y=7x+3=7\cdot 6+3=42+3=45\\\\y=45:5=9\\\\Otvet: \ (6 \ ; \ 9)$

Answer 2

решала с проверкой)))))))))))