Question

the l,b,h of a room is 6 m ,4.5 m ,3 m .find the cost of whitewashing the walls of the room and the ceiling at the rate of 8 per meter square

Answer 1

Use formula
Area of 5walls = 2h(l+b)+lb

Answer 2

Total surface area of the room =
2( 6*4.5 + 4.5*3 + 3*6 )
= 2(27 + 13.5 + 18)
=2(58.5)
= 117m²

Cost of whitewashing =
117*8
= 936

Also food for thought
When you whitewash a room, it becomes smaller