A 20-M² Thermopane Window Is Constructed,using Two Layers of Glass 4

A 2.0-m² Thermopane window is constructed,using two layers of glass 4.0 mm thick,separated by an air space of 5.0 mm.If the temperature difference is 20 $\degree$ C from the inside of the house to the outside air,what is the rate of heat flow through this window? (Thermal conductivity for glass is 0.84 J/s*m* $\degree$ C and for air 0.023 4 J/s*m* $\degree$ C. )

A) 7 700 W
B) 1 900 W
C) 547 W
D) 180 W