The cold water pipe can fill a tank in 20 minutes and the hot water pipe in 30 minutes. A person leaves the place after turning on both pipes simultaneously and returns at the moment when the tank was supposed to be completely full but he found that the waste pipe was also open because of which the time taken to fill the tank is 15 minutes more than the usual time. Find the time in which the waste pipe can empty the full tank?
1
\(19(\frac{3}{5})\) minutes
2
\(20(\frac{3}{5})\) minutes
3
\(20(\frac{2}{5})\) minutes
4
\(21(\frac{3}{5})\) minutes
5
None of these