Simplify \(\frac{(x^2-9)(9x^2-1)}{\left(x-\frac{1}{3}\right)\left(1-\frac{x}{3}\right)}\times\frac{9}{\left(x+\frac{1}{3}\right)\left(1+\frac{x}{3}\right)}\).
Pipe P can fill \( \frac{2}{7} \) part of a tank in 18 hours, and pipe Q can fill \( \frac{5}{9} \) part of the same tank in 25 hours. Both P and Q were kept open for 3 hours, then both were closed. Pipe R alone was then opened and it emptied the water in the tank in 8 hours. Pipes P, Q and R together can fill the empty tank in: