Two pipes A and B can fill a tank in 20 minutes and 30 minutes

Two pipes A and B can fill a tank in 20 minutes and 30 minutes respectively. If both pipes are opened together, the time taken to fill the tank is :

As per the given in question , we have

Part of the tank filled by both pipes in one minute =	1	+	1
	20		30

Required time =	20 × 30	= 12 minutes
	50

We can find required answer with the help of given formula :
Here, p = 20, q = 30

Required time =		pq		minutes.
		p + q

Required time =		20 × 30		minutes.
		20 + 30

Required time = 12 minutes.