Question

30 балов
5x-7y=57
9x-7y=83

Answer 1

$\displaystyle\bf\\\left \{ {{5x-7y=57 \ |\cdot (-1)} \atop {9x-7y=83}} \right. \\\\\\+\left \{ {{-5x+7y=-57} \atop {9x-7y=83}} \right. \\-----------\\-5x+7y+9x-7y=-57+83\\\\4x=26\\\\x=26:4=6,5\\\\7y=5x-57=5\cdot 6,5-57=32,5-57=-24,5\\\\y=-24,5:7=-3,5\\\\\\Otvet \ : \ (6,5 \ ; \ -3,5)$