Write each of the following ratios in its simplest form.

a) [[$ 1 \displaystyle\frac {1} {2} : 2 $]] = :

b) [[$ 4 : \displaystyle\frac {1} {4} $]] = :

c) [[$ \displaystyle\frac {4} {7} : 2 $]] = :

d) [[$ 3 \displaystyle\frac {5} {6} : 2 \displaystyle\frac {1} {2} $]] = :

e) [[$ 2 \displaystyle\frac {3} {4} : 1 \displaystyle\frac {1} {3} $]] = :