An oven wall consists of a $0\mathrm{.}635-$cm$-$thick layer of steel $($ks $=15$ W$/$m$$K$)$ and a layer of brick $($kb $=0\mathrm{.}72$ W$/$m$$K$)$ as shown in the figure below. At steady state, the temperature decreases by $0\mathrm{.}7\backslash$deg C across the steel layer. The interface of the steel and brick layers is $300\backslash$deg C$.$

a$)$

At steady state, how is the heat transfer rate through the steel related to the heat transfer rate through the brick? Justify your answer using ideas from thermodynamics $($e$.$g$.,$ systems and energy balances$).$

b$)$

If the temperature of the outer surface of the brick must be no greater than $40\backslash$deg C to avoid burns if people accidentally touch the hot surface, determine the thickness of brick, in cm$,$ that ensures this safety condition is met.

c$)$

What is the rate of conduction, in kW$,$ per m$2$ of wall surface area?