A double$-$pane window consists of two $5-$mm$-$thick layers that are separated by a $10-mm$ air gap $(k_{\text{a}\text{i}\text{r}}=$

$0\mathrm{.}025\frac{W}{m}*K.$ The heat flow through the air gap is assumed to be by conduction. The inside and outside

air temperatures are $25C$ and $-20C,$ respectively. The inside $5-$mm$-$thick layer is made of glass

$\frac{W}{m}*K,$ and the outside $5-$mm$-$thick layer is made of glass and wood combination, with $\frac{2}{3}$ glass

$\frac{W}{m}*K$ and $\frac{1}{3}wd(0\mathrm{.}10\frac{W}{m}*K).$ Determine the average heat flux through this window.