There are three pipes in a tank. If pipe A is opened, the tank will be filled in 10 minutes. If pipe B is opened the tank will be filled in 12 minutes. If pipe C is opened, the tank will be emptied in 15 minutes. And through the leakage at the bottom, the tank will be emptied in 20 minutes. If all three pipes are opened together without closing the leakage, in how many minutes will the tank be filled?