a) $0.4=\frac{4}{10}=\frac{2}{5}$

$0.08=\frac{8}{100}=\frac{2}{25}$

$0.15=\frac{15}{100}=\frac{3}{20}$

$1.375=1\frac{375}{1000}=1\frac{3}{8}$

$14.35=14\frac{35}{100}=14\frac{7}{20}$

$0.84=\frac{84}{100}=\frac{21}{25}$

b) $\frac{3}{4}=0.75$

$\frac{5}{8}=0.625$

$3\frac{1}{2}=3.5$

$4\frac{2}{5}=4.4$

$1\frac{9}{20}=1.45$

$\frac{11}{25}=0.44$