Three rods `AB,BC` and `BD` made of the same materical and having the same area of cross

Three rods `AB,BC` and `BD` made of the same materical and having the same area of cross section have been joined as shown is the The ends `A,C` and `D` are held at temperatures `20^(@)C` Cand `80^(@)C` respectively If each rod is of same length then find the temperature at the junction `B` of the three rods .