Question 431386
Filling the pool is 1 job									
Pipe A + pipe B  takes	25	hours					
So they will do	1/25of the job in 1 hour				
Pipe A alone takes 40	hours						
It does 1/40	of the job in 1 hour				
If Pipe A does the job in x hours it does 1/x of the job in 1hour									
1/25-1/40=1/x	
LCD =	200								
(8-5)/200=1/x	
3/200=1/x					
Cross multiply									
3x=200						
x=67 hours