Solve [[$ x $]].

a) [[$ \displaystyle\frac {x} {4} = 9 $]]



[[$ x = $]]

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



[[$ x = $]]

c) [[$ \displaystyle\frac {1} {x} = 12 $]]



[[$ x = $]]

d) [[$ \displaystyle\frac {56} {7} = x $]]



[[$ x = $]]