Laske.

a) [[$ \dfrac{2}{5} \cdot \dfrac{5}{2} $]] =

b) [[$ \dfrac{9}{10} \cdot \dfrac{10}{9} $]] =

c) [[$ \dfrac{8}{9} \cdot \dfrac{9}{8} $]] =

d) [[$ \dfrac{100}{105} \cdot \dfrac{105}{100} $]] =