Given: Each thermal resistance in the network shown has a value of $R_{th}=0\mathrm{.}20\frac{K}{W}.$

Find: a$)$ Calculate the sum of thermal resistances for the network.

b$)$ Calculate the heat transfer rate through the network if the temperature difference across the network is $100C.$

c$)$ What is the symbol used for overall heat transfer coefficient? How would you calculate the overall heat transfer coefficient for this network?