Tap A takes three hours to fill a drum,tap B takes five hours to empty a drum,how long will the drum be filled up if two taps are together?

To solve this problem, we need to find the combined rate at which the two taps fill or empty the drum.

Tap A fills the drum at a rate of 1/3 drum per hour, while tap B empties the drum at a rate of 1/5 drum per hour.

When both taps are working together, we need to add their rates:

1/3 - 1/5 = 5/15 - 3/15 = 2/15

So, when both taps are working together, they fill the drum at a rate of 2/15 drum per hour.

To find out how long it will take for the drum to be filled, we need to divide the total volume of the drum (1 drum) by the combined rate:

1 / (2/15) = 15/2 = 7.5 hours

Therefore, it will take 7.5 hours for the drum to be filled when both taps are working together.