The bottom face of a horizontal slab of thickness $6 \:mm$ is maintained at $300^{\circ}C$. The top face is exposed to a flowing gas at $30^{\circ}C$. The thermal conductivity of the slab is $1.5 \:W\: m^{-1}\: K^{-1}$ and the convective heat transfer coefficient is $30\: W\: m^{-2}\:K^{-1}$. At steady state, the temperature (in $^{\circ}C$) of the top face is ______________