−7x + 4x − 8x = −9,9
−11x = −9,9
x = −9,9 : (−11)
x = 0,9

0,6y − 1,9y − 0,5y = 0,54
−1,8y = 0,54
y = 0,54 : (−1,8)
y = −0,3

$\frac{1}{8}x - \frac{2}{3}x + \frac{1}{2}x = -\frac{5}{18}$
$\frac{3}{24}x - \frac{16}{24}x + \frac{12}{24}x = -\frac{5}{18}$
$-\frac{1}{24}x = -\frac{5}{18}$
$x = -\frac{5}{18} : (-\frac{1}{24})$
$x = -\frac{5}{18} * (-\frac{24}{1})$
$x = -\frac{5}{3} * (-\frac{4}{1})$
$x = \frac{20}{3}$
$x = 6\frac{2}{3}$

$-9\frac{5}{6}b + 2\frac{3}{4}b + 1\frac{5}{12}b = 1\frac{7}{27}$
$-8\frac{22}{12}b + 2\frac{9}{12}b + 1\frac{5}{12}b = \frac{34}{27}$
$-5\frac{8}{12}b = \frac{34}{27}$
$b = \frac{34}{27} : (-5\frac{2}{3})$
$b = \frac{34}{27} : (-\frac{17}{3})$
$b = \frac{34}{27} * (-\frac{3}{17})$
$b = \frac{2}{9} * (-\frac{1}{1})$
$b = -\frac{2}{9}$