Question

Tap A can fill tank in 8 mins. Outlet B can empty the tank in 12 minutes.If both are kept open, how long will it take to fill the tank?

Answer 1

Tap A in 1 minute=1/8 
Tap B in 1 minute=1/12
Tap A + Tap B  = 1/8 - 1/12
                         =1/24
                            
Therefore  24 minutes are taken to fill the tank

Answer 2

I hope that it will helps you.