TeX source:
\begin{array}{rcl}\genfrac{}{}{1pt}{0}{\frac{14a^2 w}{9az^{17}}}{\frac{28wz}{123a}} &=& \dfrac{14a^2 w}{9az^{17}} : \dfrac{28wz}{123a} \\\\&=& \dfrac{14a^2 w}{9az^{17}} \cdot \dfrac{123a}{28wz} \\\\&=& \dfrac{a^2}{3z^{17}} \cdot \dfrac{41}{2z} \\\\ &=& \dfrac{41a^2}{6z^{18}} \end{array}