Two pipes A and B can fill a cistern in 12 minutes and 15 minutes respectively while a third pipes C can empty the full cistern in 6 minutes. A and B are kept open for 5 minutes in the beginning and then C is also opened. In what time is the cistern emptied?

• ক 42minutes
• খ 40minutes
• গ 45minutes ✅ সঠিক উত্তর
• ঘ 48minutes