I can't understand your question properly, but from what I have understood I will give you the solution.
Let the number be x.
Then,
6x * 9x = 10(9x-6x)
=> 54x^2 = 30x
=> 54x^2 -30x = 0
=> x(54x-30) = 0
so either x = 0
or 54x-30 =0
=> 54x = 30
=> x = 30/54 =0.55555555555
so,
x = 0 or x = 0.5555555555555