A room is twice as long as it is broad and its height is 8 m. if the cost of painting its walls at Rs. 20 per m² is Rs 9600 , find the cost of carpeting its floor at Rs. 400 per m²​​

let breadth be X

length = 2x

height = 8m

rate of painting the four wall= 20/m^2

cost of painting=9600

Area of four wall= cost of painting / rate

= 9600/20

= 480m^2

again,

Area of four wall = 2 h(l+b)

or, 480=2×8(X+2x)

or, 480/16=3x

or, 30/3=X

or, X= 10m

again,

2x= 2×10m=20m

again,

Area of floor = length × breadth

= 20×10

=200m^2

again,

rate of carpeting the floor= 400/m^2

cost of carpeting the floor = rate × area

= 400× 200

= Rs. 80000

step-by-step explanation: