TeX Quellcode:

\begin{array}{rclcll}\dfrac{12-x}{4x-8} &\leq & 1 &\vert & \cdot\left(4x-8\right)\\12-x &\geq & 4x-8 &\vert & +8+x\\20 &\geq & 5x &\vert & :5\\4 &\geq & x \\x &\leq& 4\end{array}