The length of a hall is 18 m and the width 12 m. The sum of the areas of the floor and the flat roof is equal to the sum of the areas of the four walls. Find the height of the wall.
Given,
Length of hall = 18 m
Width of hall = 12 m
Let height of hall = h metre
Then,
Sum of area of floor & flat roof = 
Sum of area of 4 walls = 
Now,
= 
= 
Height of hall = 7.2 metre
15