Two pipes can separately fill a tank in 20 hrs and 30 hrs respectively. Both these pipes are opened simultaneously and after the tank is $$\ \frac{1}{3}$$rd full, a leak develops in the tank through which $$\frac{1}{3}$$rd of water supplied thereafter by both pipes gets leaked out. The total time (in hours) taken to fill the tank is 

A

18

B

16

C

15

D

12