a. \(\frac{10}{12}\div\frac{6}{25}=\frac{5}{6}\times\frac{25}{6}=\frac{125}{36}\)
b. \(1,7\div2,85=\frac{1,7}{2,85}=\frac{1,7\times100}{2,85\times100}=\frac{170}{285}\)
c, \(\frac{1}{5}\div0,25=\frac{1}{5}\div\frac{1}{4}=\frac{1}{5}\times4=\frac{4}{5}\)