a) $\frac{1}{6}\;+\;(...) = \frac{-2}{3}$.

$\Rightarrow (...) = \frac{-2}{3}\;-\;\frac{1}{6}$.

$\Rightarrow (...) = \frac{-4}{6}\;-\;\frac{1}{6}$.

$\Rightarrow (...) = \frac{-4\;-\;1}{6}$.

$\Rightarrow (...) = \frac{-5}{6}$

b) $\frac{-2}{3}\;+\;(...) = \frac{3}{5}$.

$\Rightarrow (...) = \frac{3}{5}\;-\;\frac{-2}{3}$.

$\Rightarrow (...) = \frac{9}{15}\;+\;\frac{10}{15}$.

$\Rightarrow (...) = \frac{9\;+\;10}{15}$.

$\Rightarrow (...) = \frac{19}{15}$

c) $\frac{1}{6}\;-\;(...) = \frac{3}{24}$.

$\Rightarrow (...) = \frac{3}{24}\;-\;\frac{1}{6}$.

$\Rightarrow (...) = \frac{3}{24}\;-\;\frac{4}{24}$.

$\Rightarrow (...) = \frac{3\;-\;4}{24}$.

$\Rightarrow (...) = \frac{-1}{24}$

d) $\frac{-7}{19}\;-\;(...) = 0$.

$\Rightarrow (...) = \frac{-7}{9}\;-\;0$.

$\Rightarrow (...) =\frac{-7}{9}$.