pH = - log(H+)
9 = - log(H+)
10^(-9)= H+
we need to find less basic solution,i.e. more acidic so more H+ concentration in the new solution.
so
H+ in new solution = 10^(-9) * 1000 = 10(-6)
pH of new solution = -log(10^(-6)) = 6
so pH 9 is 1000 times more basic than pH 6.