$\text{a)}$  

$\frac{5}{2}=2\frac{1}{2}=2\frac{5}{10}=2,5$  

$\frac{12}{5}=2\frac{2}{5}=2\frac{4}{10}=2,4$  

$\frac{17}{4}=4\frac{1}{4}=4\frac{25}{100}=4,25$  

$\frac{7}{16}=\frac{4375}{10000}=0,43375$  

$\frac{26}{25}=1\frac{1}{25}=1\frac{4}{100}=1,04$  

$8\frac{7}{20}=8\frac{35}{100}=8,35$  

$14\frac{5}{10}=14,5$  

$3\frac{37}{100}=3,37$  

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$\text{b)}$  

$\frac{1}{9}=0,111\dots =0,\left(1\right)$  

$\frac{1}{12}=0,08333\dots =0,08\left(3\right)$  

$\frac{5}{36}=0,13888\dots =0,13\left(8\right)$  

$\frac{8}{15}=0,5333\dots =0,5\left(3\right)$  

$1\frac{2}{7}=1,28571428571428\dots =1,\left(285714\right)$