A set (P) of 10 pipes can fill 40% of a tank in 8 minutes. Another set (Q) of 6 pipes fills half of the tank in 10 minutes. A third set (R) of 8 pipes can empty three-fourths of the tank in 15 minutes. If two-fifths of the pipes of set P are closed, only half of the pipes of set Q are open, and all pipes of set R are open, then how long will it take to fill 30% of the tank?