1. A pipe fills a pool in 4 hours, another pipe drains a full pool in 6 hours. How long will it take to fill the pool if both pipes are opened?

2. A pool is connected with 3 pipes. Two pipes fill the pool and one drains it. It takes 3 hours for first pipe to fill the pool and 2 hours for the 2nd one. The third pipe drains a full pool in 6 hours. How long will it take to fill the pool if all pipes are opened?

Ugh, they seem so simple lol, but I can't solve them, just a few guidelines would help..
I'm off to sleep now, so thanks to anyone who helps.

1) pipe 1 fills the pool 1/4 in 1 hour. Pipe 2 drains the pool 1/6 in 1 hour
you're looking for the condition:

t(\frac{1}{4}-\frac{1}{6}) = 1

solve for t

2) you can do the same for this one, have a go and tell me what you come up with.

Let me know if you need further help.

Thanks!
So is it 12h for the first one and 1.5h for the 2nd exercise?

That's what I got :)

Well done!