Pipe A can fill an empty tank in 6 hours and pipe B in 8

Pipe A can fill an empty tank in 6 hours and pipe B in 8 hours. If both the pipes are opened and after 2 hours pipe. A is closed, how much time B will take to fill the remaining tank?

As per the given in question , we have

Part of tank filled by pipes A and B in 2 hours = 2		1	+	1
		6		8

Part of tank filled by pipes A and B in 2 hours = 2		4 + 3		=	7
		24			12

Remaining part = 1 –	7	=	5
	12		12

This part is filled by pipe B.

∴ Required time =	5	× 8
	12

Required time =	10	hours	= 3	1	hours
	3			3