Three pipes A B and C can fill a tank in 6 hours together All three pipes are opened for 2 hours and...........

Quantitative Aptitude (SBI-PO) Pipes&cistern

Three pipes A, B and C can fill a tank in 6 hours together. All three pipes are opened for 2 hours, and then pipe C is closed. The remaining part of the tank is filled by pipes A and B in 7 hours. How much time will pipe C take to fill the empty tank alone?

14 hours