$\frac{9}{30}=\frac{9: 3}{30 : 3}=\frac{3}{10}$

$\frac{11}{25}=\frac{11\times 4}{25\times 4}=\frac{44}{100}$

$\frac{64}{400}=\frac{64: 4}{400 : 4}=\frac{16}{100}$

$\frac{21}{50}=\frac{21\times 2}{50\times 2}=\frac{42}{100}$

$\frac{13}{250}=\frac{13\times 4}{250\times 4}=\frac{52}{1000}$