Consider a $20-$cm thick plane wal with a thermal conductivity of $279$ Wim. $K$ and a unit surface area. The temperature of the left surface is held constant at $50C,$ whereas the right face is exposed to a flow of alr at $22C$ whth a convection heat transfer coefficlent of $15Wi{m}^{2}K.$

a$)$ What assumptions will be used in solving this problem.

b$)$ Find the right wall surface temperature