$\frac{3}{5}х = -\frac{9}{10}$
$х = -\frac{9}{10} : \frac{3}{5}$
$х = -\frac{9}{10} * \frac{5}{3}$
$х = -\frac{3}{2} * \frac{1}{1} = -1\frac{1}{2}$

$-\frac{4}{7}y = \frac{8}{21}$
$y = \frac{8}{21} : (-\frac{4}{7})$
$y = \frac{8}{21} * (-\frac{7}{4})$
$y = \frac{2}{3} * (-\frac{1}{1}) = -\frac{2}{3}$

$-\frac{5}{9}х = -1\frac{13}{27}$
$х = -1\frac{13}{27} : (-\frac{5}{9})$
$х = -\frac{40}{27} * (-\frac{9}{5})$
$х = -\frac{8}{3} * (-\frac{1}{1}) = 2\frac{2}{3}$

$-\frac{2}{3}y + 5 = 2\frac{5}{9}$
$-\frac{2}{3}y = 2\frac{5}{9} - 5$
$-\frac{2}{3}y = -2\frac{4}{9}$
$y = -2\frac{4}{9} : (-\frac{2}{3})$
$y = -\frac{22}{9} * (-\frac{3}{2})$
$y = -\frac{11}{3} * (-\frac{1}{1}) = 3\frac{2}{3}$