TeX Quellcode:

\begin{array}{rclll} \genfrac{}{}{1pt}{0}{-45x}{\frac{5y}{9x}} &=& -45x : \dfrac{5y}{9x} \cr\cr &=& -45x \cdot \dfrac{9x}{5y} \cr\cr &=& -9x \cdot \dfrac{9x}{y} \cr\cr &=& -\dfrac{81x^2}{y} \end{array}