A $1\mathrm{.}0$ m X $1\mathrm{.}5$ m double$-$pane window consists of two $4-$mm$-$thick layers of glass

$($k $=0\mathrm{.}78$ W$/$m$$K$)$ that are separated by a $5-$mm air gap $($kair $=0\mathrm{.}025$ W$/$m$$K$).$ The heat flow

through the air gap is assumed to be by conduction. The inside and outside air temperatures are

$20$C and $-20$C$,$ respectively, and the inside and outside heat transfer coefficients are $40$ and $20$

W$/$m$2$K$.$ Determine $($a$)$ the daily rate of heat loss through the window in steady operation and $($b$)$

the temperature difference across the largest thermal resistance