A room 5m x 8m is to be carpeted leaving a margin of 10 cm from each wall. If the cost of the carpet is Tk. 18 per sq. meter, the cost of carpeting the room will be:

The room dimensions are 5m x 8m. However, you need to leave a margin of 10 cm from each wall, which is equivalent to 0.1m. So, the effective dimensions for carpeting are (5m - 2 * 0.1m) x (8m - 2 * 0.1m).

Effective length = 5m - 2 * 0.1m = 4.8m Effective width = 8m - 2 * 0.1m = 7.8m

Now, calculate the area of the room to be carpeted:

Area = Effective length * Effective width Area = 4.8m * 7.8m = 37.44 sq. meters

Now, you know that the cost of the carpet is Tk. 18 per square meter. You can calculate the total cost:

Total Cost = Area * Cost per sq. meter Total Cost = 37.44 sq. meters * Tk. 18/sq. meter

Total Cost = Tk. 673.92

So, the cost of carpeting the room will be Tk. 673.92.