$a) \dfrac{-2}{33} + \dfrac{5}{55} = \dfrac{-2}{33} + \dfrac{1}{11} = \dfrac{1}{33}$
$b) \dfrac{-3}{26} + 2\dfrac{4}{69} = 1,9$
$c) \dfrac{-1}{12} - (2\dfrac{5}{8} - \dfrac{1}{3}) = \dfrac{-19}{8}$
$d) -1,75 - 9 - (\dfrac{1}{9} - 2\dfrac{1}{18}) = -1,75 - 9 - (\dfrac{-35}{18}) = \dfrac{-317}{36}$
$e) \dfrac{-5}{6} - (\dfrac{-3}{8} + \dfrac{1}{10}) = \dfrac{-5}{6} - (\dfrac{-11}{40}) = \dfrac{-67}{120}$
$f) \dfrac{2}{5} + (\dfrac{-4}{3}) + (\dfrac{-1}{2}) = \dfrac{-43}{30}$
$g) \dfrac{3}{12} - (\dfrac{6}{15} - \dfrac{3}{10}) = \dfrac{1}{4} - \dfrac{1}{10} = \dfrac{3}{20}$