Pipes A and B can fill a tank in 6 hours and 15 hours, respectively. Pipe C is a drain pipe. When all three pipes are opened together for 6 hours, 65% of the tank is filled. Initially, pipes A and C are opened together for 8 hours and then C is closed and B is opened. In how many hours will pipes A and B together fill the remaining part of the tank?

Three taps A, B, and C can fill an empty tank in 30 minutes, 20 minutes, and 10 minutes respectively. When the tank is empty, all three taps are opened. Taps A, B, and C release chemical solutions P, Q, and R respectively. What is the proportion of solution R in the tank after 3 minutes?

Two inlet pipes J and T can fill a tank in 120 minutes and 144 minutes respectively. If an outlet pipe Z is opened along with them, all three pipes together fill the tank in 240 minutes. How long will pipe Z alone take to empty the full tank?