The volume of a wall, 5 times as high as it is broad and 8 times as long as it is high, is 12.8 cu. meters. Find the breadth of the wall.

Let the breadth of the wall be x metres. 

Then, Height = 5x metres and Length = 40x metres.  

x * 5x * 40x = 12.8   

=> $x3 =12.8/200 = 128/2000 =64/1000$  

=> x = 4/10 m  

=> x = (4/10)*100 = 40 cm