Add or subtract as indicated. Express your results in simplest form.x^2/x-3-9/(x-3)

What have written is ambiguous unless you insert parentheses where they are needed to explain the order of operation.

If you mean
x^2/(x-3) -9/(x-3) ,
then rewrite it as
(x^2-9)/(x-3) = (x+3)(x-3)/(x-3) = x+3