Laske.

a) [[$ \dfrac{2}{3} - \dfrac{5}{2} + \dfrac{1}{2} $]] =

b) [[$ \dfrac{1}{6} + \dfrac{3}{5} -\dfrac{2}{3} $]] =

c) [[$ 2 - \dfrac{4}{5} + \dfrac{1}{2} $]] =