Cancel
$\frac{30}{100}:{\quad}\frac{3}{10}$
$=\frac{3}{10}\times \frac{4}{6}$
Cancel
$\frac{4}{6}:{\quad}\frac{2}{3}$
$=\frac{3}{10}\times \frac{2}{3}$
Cross-cancel common factor:
$ 3$
$=\frac{2}{10}$
Cancel the numbers:
$ \frac{2}{10}=\frac{1}{5}$
$=\frac{1}{5}$