TeX source:

\begin{array}{crcrcrcr} \text{I} & & & & & c &=& 0 \cr \text{II} & \dfrac{1}{9}a &+& \dfrac{1}{3}b &+& c &=& -\dfrac{1}{3} \cr \text{III} & \dfrac{4}{9}a &+& \dfrac{2}{3}b &+& c &=& 0 \end{array}