Four pipes P, Q, R and S are connected to a tank. Pipe P, Q, R and S can fill the whole tank in 300/37 minutes. Ratio of time taken by pipe P to fill the tank when operating alone and pipe Q to fill the tank when operating alone is 3 : 2, pipe Q is 20% more efficient then pipe R and time taken by pipe S is 10 minutes more than pipe R. Find difference between time taken by pipe Q and pipe P to fill up the tank alone.