Three conductors of same length having thermal conductivity $$k_1, k_2 \text{ and } K_3$$ are connected as shown in figure.

Area of cross sections of $$ 1^{st} \text{ and }2^{nd}$$ conductor are same and for $$3^{rd}$$ conductor it is double of the $$1^{st}$$ conductor. The temperatures are given in the figure. In steady state condition, the value of 0 is _______ $$^oC$$.
$$(\text{Given }:k_1=60Js^{-1}m^{-1}K^{-1},k_2= 120Js^{-1}m^{-1}K^{-1}, k_3= 135Js^{-1}m^{-1}K^{-1})$$