(2) $\begin{aligned} f(x) & =x^{2}-3 x \\ g(x) & =3-x \\ \text { find } & =(f-g)(9)=\end{aligned}$

Step 1 ：Find the value of f(9) by substituting x = 9 in the function f(x) = x^2 - 3x. This gives f(9) = 9^2 - 3*9 = 54.

Step 2 ：Find the value of g(9) by substituting x = 9 in the function g(x) = 3 - x. This gives g(9) = 3 - 9 = -6.

Step 3 ：Subtract g(9) from f(9) to get (f-g)(9) = f(9) - g(9) = 54 - (-6) = 60.

Step 4 ：So, the final answer is \(\boxed{60}\).