TeX Quellcode:

\begin{array}{rclll} 13m+m+30-23m-45+17+12m &=& -31 \cr 3m+2 &=& -31 & \vert & -2 \cr 3m &=& -31-2 \cr 3m &=& -33 & \vert & :3 \cr m &=& -11 \end{array}