Thermal conduction - junction temperature

2022 Phase 2 1 question

1. Two rods one made of copper and other made of steel of the same length and same cross sectional area are joined together. The thermal conductivity of copper and steel are 385 J s$^{-1}$K$^{-1}$m$^{-1}$ and 50 J s$^{-1}$K$^{-1}$m$^{-1}$ respectively. The free ends of copper and steel are held at $100^\circ C$ and $0^\circ C$ respectively. The temperature at the junction is, nearly: