$\frac{4}{16} = \frac{2}{8} = \frac{1}{4}$

$\frac{2}{10} = \frac{1}{5}$

$\frac{3}{12} = \frac{1}{4}$

$\frac{8}{16} = \frac{4}{8} = \frac{2}{4} = \frac{1}{2}$

$\frac{6}{20} = \frac{3}{10}$