$\frac{4}{5}$ : $\frac{4}{7}$ = $\frac{4}{5}$ × $\frac{7}{4}$ = $\frac{28}{20}$ = $\frac{7}{5}$
$\frac{9}{5}$ : $\frac{3}{10}$ = $\frac{9}{5}$ × $\frac{10}{3}$ = $\frac{90}{15}$ = $\frac{6}{1}$ = 6
$\frac{1}{6}$ : $\frac{1}{3}$ = $\frac{1}{6}$ × $\frac{3}{1}$ = $\frac{3}{6}$ = $\frac{1}{2}$
$\frac{1}{9}$ : $\frac{1}{6}$ = $\frac{1}{9}$ × $\frac{6}{1}$ = $\frac{6}{9}$ = $\frac{2}{3}$