TeX Quellcode:

\genfrac{}{}{1pt}{0}{\frac{14c}{-15}}{\dfrac{-21c}{18a}} = \dfrac{14c}{-15} : \left(\dfrac{-21c}{18a} \right) = -\dfrac{14c}{15} \cdot \left(-\dfrac{6a}{7c} \right) = -\dfrac{2}{5} \cdot \left( -\dfrac{2a}{1} \right) = \dfrac{4a}{5}