One pipe can empty a tank in 45 minutes while a second pipe can empty it in 60 minutes. If both pipes are opened at the same time, how long will it take to drain the tank?

It will take 25.7 minutes when they are working together

Step-by-step explanation:

Here, we want to know how long it will take both pipe working together to drain the tank

Let the volume of water to be drained be xL

for the first one, rate is

x/45 L/minutes

for the second x/60 L/minutes

Joint rate will be

x/45 + x/60 = 4x + 3x/180 = 7x/180

Now go get the time involved here, we simply divide the volume by the rate

That would be;

x divided by 7x/180

= x * 180/7x

= 180/7 = 25.7 minutes