TeX Quellcode:

\begin{array}{crcrcl} \text{I} & a - b &=& -2 &\vert& +b \cr \text{III} & 4a + 2b &=& 8 \cr\cr \text{I} & a &=& -2 + b \cr \text{III} & 4a + 2b &=& 8 \cr \cr \text{I in III} & 4\left(-2 +b \right) +2b &=& 8 \cr & -8 + 4b + 2b &=& 8 &\vert& +8 \cr & 6b &=& 16 &\vert& :6 \cr & b &=& \dfrac{8}{3} \cr\cr \text{b in I} & a &=& -2 + \dfrac83 \cr & a &=& \dfrac{2}{3} \end{array}