$12{,}50=\dfrac{1250}{100}$

$12{,}50$% $=\dfrac{1250}{100\cdot100}=\dfrac{1250}{10000}=\dfrac{1}{8}$

$0{,}05= \dfrac{5}{100}=\dfrac{1}{20}$

$0{,}428571=\dfrac{428571}{100000}\approx\dfrac{3}{7}$