Laske.

a) [[$ \dfrac{7}{8} - \dfrac{2}{3} $]] =

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

c) [[$ 1 \dfrac{1}{3} - \dfrac{1}{4} $]] =

d) [[$ 2 \dfrac{1}{2} - \dfrac{5}{6} $]] =