IBPS RRB PO Prelims 20 Aug 2022 Shift 1 Paper

Pipes A, B and C together can fill a tank in 6 hours. Pipes A and B together can fill the tank in 9 hours. If pipes A, B and C are opened simultaneously, and after 3 hours, pipes A and B are closed, then how many hours will C alone require to fill the remaining tank?