Aloha :)
$$\text{a)}\;\;\frac{3}{5}=\frac{3\cdot2}{5\cdot2}=\frac{6}{10}=0,6$$$$\text{b)}\;\;\frac{9}{20}=\frac{9\cdot5}{20\cdot5}=\frac{45}{100}=0,45$$$$\text{c)}\;\;\frac{11}{25}=\frac{11\cdot4}{25\cdot4}=\frac{44}{100}=0,44$$$$\text{d)}\;\;\frac{17}{50}=\frac{17\cdot2}{50\cdot2}=\frac{34}{100}=0,34$$$$\text{e)}\;\;\frac{4}{16}=\frac{4:4}{16:4}=\frac{1}{4}=\frac{1\cdot25}{4\cdot25}=\frac{25}{100}=0,25$$