a) \(\frac{3}{10}\) : \(\frac{2}{5}\) = \(\frac{3}{10} \times \frac{5}{2}\) = \(\frac{3 \times 2}{10 \times 5}\) = \(\frac{15}{20}\) = \(\frac{3}{4}\) ;
b) \(\frac{4}{7}\) : \(\frac{3}{11}\) = \(\frac{4}{7} \times \frac{11}{3}\) = \(\frac{4 \times 3}{7 \times 11}\) = \(\frac{44}{21}\) ;