TeX Quellcode:
\begin{array}{rclll} 3x \, (-4x-10) &=& (2-2x) \cdot (6x+15) \cr -12x^2-30x &=& 12x+30-12x^2-30x & \vert & +12x^2+30x-12x \cr -12x^2+12x^2-30x+30x-12x &=& 30 \cr -12x &=& 30 & \vert & :(-12)\cr x &=& -\dfrac{30}{12} = -\dfrac{5}{2} \end{array}