A plane wall with thickness $3($m$)$ and area $18($m$2)$is made of material with heat thermal conductivity $1\mathrm{.}2($W$/$m$.$K$).$The air on one side of the wall has temperature $293($K$)$and heat transfer coefficient from the air to the$$wall surface is $6($W$/$m$2$ K$).$On the other side of the wall the air temperature is $255($K$)$and the heat transfer coefficient is $15($W$/$m$2$ K$).$

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Calculate the wall surface temperature Ts$1($K$)$on side $1($facing air with temperature T$1).$