Tính

a) \[\frac{3}{4}:\frac{9}{{20}} = \frac{3}{4} \times \frac{{20}}{9} = \frac{{\bcancel{3} \times \bcancel{4} \times 5}}{{\bcancel{4} \times 3 \times \bcancel{3}}} = \frac{5}{3}\]

\[\frac{7}{6} \times \frac{3}{{14}} = \frac{{\bcancel{7} \times \bcancel{3}}}{{2 \times \bcancel{3} \times \bcancel{7} \times 2}} = \frac{1}{4}\]