To simplify this expression, we need to find a common denominator for all three fractions.

The common denominator for the fractions 3/x-3, x+15/x^2-9, and 2/x is x(x^2 - 9).

Now, we can rewrite each fraction with the common denominator:

3(x^2 - 9)/x(x^2 - 9) - (x(x + 15))/x(x^2 - 9) - 2(x)(x - 3)/x(x^2 - 9)

Simplify each fraction:

= 3x^2 - 27/x(x^2 - 9) - x^2 -15x/x(x^2 - 9) - 2x^2 + 6x/x(x^2 - 9)

Combine like terms:

= (3x^2 - x^2 - 2x^2 - 27 - 15x + 6x)/x(x^2 - 9)

= 0

Therefore, the simplified expression is 0.