$a)\frac{28}{100}=0,28$

$3\frac{5}{10}=3,5$

$7\frac{7}{100}=7,07$

$\frac{7}{1000}=0,007$

$\frac{152}{1000}=0,152$

$5\frac{18}{1000}=5,018$

 

$b)\frac{13}{10}=1,3$

$\frac{87}{10}=8,7$

$\frac{122}{100}=1,22$

$\frac{323}{100}=3,23$

$\frac{209}{100}=2,09$

$\frac{1247}{1000}=1,247$