There is a pool in which there is a certain amount of water. The pool is equipped with a water inlet pipe and several identical drainage pipes. If the water inlet pipe and five drainage pipes are opened for 8 minutes at the same time, all the water in the pool can be discharged. If the water inlet pipe and eight drainage pipes are opened for 4 minutes at the same time, all the water in the pool can be discharged, Turn off six of the drain pipes. In a minute, the pool will be empty. How many drain pipes are installed on the pool? (please analyze the answer, otherwise do not choose the best answer!)

There is a pool in which there is a certain amount of water. The pool is equipped with a water inlet pipe and several identical drainage pipes. If the water inlet pipe and five drainage pipes are opened for 8 minutes at the same time, all the water in the pool can be discharged. If the water inlet pipe and eight drainage pipes are opened for 4 minutes at the same time, all the water in the pool can be discharged, Turn off six of the drain pipes. In a minute, the pool will be empty. How many drain pipes are installed on the pool? (please analyze the answer, otherwise do not choose the best answer!)

Set a water inlet pipe to fill the water in X minutes, set a water outlet pipe to drain the water in Y minutes, and set Z drainage pipes on the pool. From "the water inlet pipe and 5 drainage pipes can be opened for 8 minutes at the same time to drain all the water in the pool", we get: (5 / Y-1 / x) * 8 = 1 (1)