Solve the proportions.

a) [[$ \displaystyle\frac {x} {6} = \displaystyle\frac {12} {18} $]]



[[$ x = $]]

b) [[$ \displaystyle\frac {2} {3} = \displaystyle\frac {x} {24} $]]



[[$ x = $]]

c) [[$ \displaystyle\frac {x} {7} = \displaystyle\frac {8} {14} $]]



[[$ x = $]]

d) [[$ \displaystyle\frac {14} {3} = \displaystyle\frac {7} {x} $]]



[[$ x = $]]