$a)\frac{7}{11}=7:11=0,636363\dots =0,\left(63\right)$

$b)\frac{5}{90}=5:90=0,055555\dots =0,0\left(5\right)$

$c)\frac{8}{111}=8:111=0,072072\dots =0,\left(072\right)$