The width of one wall of a classroom in Chemical Engineering is $12$ m and the height is $3$ m$,$ and the interior surface temperature is $15\backslash$deg C$.$ If the temperature of this classroom is $25\backslash$deg C$,$ find the amount of heat transferred between the wall and the classroom. If the classroom wall was $2\mathrm{.}75$ m long, calculate the percentage decrease in the amount of heat lost from the wall.