Q$3)$ The system shown below is a thermal model of Dr$.$ Farrow's office, including the office itself, the offices next door, and the outside air. Heaters in the THRN offices work by pumping warm air into the offices. The heater in Dr$.$ Farrow's office $(\backslash (\backslash$mathrm$\{$q$\}\_\{\backslash$mathrm$\{$in$\}\}\backslash ))$ is working perfectly, but the heaters in the adjacent offices are broken. Dr$.$ Farrow wants to model the temperature in his office under these conditions. He assumes that the outside temperature is constant and will use it as the reference.

a$)$ Indicate, on the figure above, which sections of this system should be assumed to be perfectly insulated. Justify your answer.

b$)$ Treat each room as a subsystem and draw the interconnected block diagram. In your block diagram, clearly label all blocks and signals.