A Thermopane window of area 10 m2 is constructed of two layers of glass, each 10 mm thick, separated by an air space of 5 mm

A Thermopane window of area 10 m2 is constructed of two layers of glass, each 10 mm thick, separated by an air space of 5 mm. If the inside is at 20 oC and the outside is at -30 oC. The thermal conductivity of the glass is 0.84 W/(moC) and the thermal conductivity of the air is 0.0234 W/(moC).
The rate of heat flow through a material of area A and thickness Δx depends on the thermal conductivity k of the material. Heat flows from the high to the low temperature side. When a steady state is reached, the same amount of heat crosses any cross sectional area per second.
The thermal conductivity k is defined through the equation ΔQ/Δt = -kA×(T2 - T1)/Δx What is the rate of heat loss through the window?
a) 1.1kW;   b) 1.9kW;   c) 2.1kW;   d) 2.3kW;   e) None of the above;