$\frac{7}{9}\times \frac{4}{5}=\frac{7\times 4}{9\times 5}=\frac{28}{45}$

$\frac{1}{5}:\frac{7}{8}=\frac{1\times 8}{5\times 7}=\frac{8}{35}$

$2\frac{1}{4}\times 3\frac{2}{5}=\frac{9}{4}\times \frac{17}{5}=\frac{153}{20}$

$1\frac{1}{5}: 1\frac{1}{3}=\frac{6}{5}: \frac{4}{3}=\frac{6}{5}\times \frac{3}{4}=\frac{18}{20}$