Gases with a temperature of $550\backslash$deg C transfer heat through a wall with an area of $6$ m$2$ to water with a temperature of $190\backslash$deg C$.$ Heat return coefficients from gas to wall $130$ W$/$m$2$K$,$ from wall to water $4600$ W$/$m$2$K$.$

Determine: all thermal resistance, thermal conductivity coefficient and heat flow, which is transferred from gases to water, for the following cases:

a$)$ Clean steel wall with a thickness of $6$ mm$.$

b$)$ The steel wall is covered with limestone $16$ mm thick on the water side and soot $1\mathrm{.}5$ mm thick on the gas side. For case $"$b$",$ find the temperature for all layers of the wall in a graphical way and draw a temperature graph.