(7, 85x - 12, 4x) * (-1, 9/91) = -2, 11/12 - 1, 2/3

[latex](7,85x-12,4x)(-1\frac{9}{91})=-2\frac{11}{12}-1\frac{2}{3}\\-4,55x*(-\frac{100}{91})=-\frac{35}{12}-\frac{5}{3}\\4,55x*\frac{100}{91}=-\frac{35}{12}-\frac{5}{3}\\\frac{455}{91}x=-\frac{35}{12}-\frac{20}{12}\\5x=-\frac{55}{12}\\x=-\frac{55}{12}:5=-\frac{55}{12}*\frac{1}{5}\\x=-\frac{11}{12}[/latex]