Let the length and the breadth of the room be 4x m and x m respectively.
Area of the four walls of the room = 2(l + b) h
= 2(4x + x) 5 = 50 x m2
Cost of papering the four walls of the room @ 70 paise per square metre
= र 50x x 0.70 = र 35x According to the question,
35x = 157.50
∴ Breadth of the room = 4.5 m
∴ Length of the room = 4 x 4.5 m = 18 m.