Electrochemistry

What is molar conductivity at zero concentration in $\Omega^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ for aluminium sulphate, if molar ionic conductivities at zero concentration of $\mathrm{Al}^{+3}$ and $\mathrm{SO}_4^{-2}$ are $189 \Omega^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ and $50.1 \Omega^{-1} \mathrm{~cm}^2 \mathrm{~mol}^{-1}$ respectively?