If the length, breadth and height of a room are 20 m, 25 m and 35 m, respectively, then what will be the total surface area of the four walls of the room?

Length of the room l=20 m

Breadth of the room b=25 m

Height of the room h=35 m

Total Surface Area of Four Walls = 2h(l + b)

Where:

h is the height of the room

l is the length

b is the breadth

Substituting the values into the formula:

Total Surface Area=2×35×(20+25) =70 × 45= $$3150 \, \text{m}^2$$