Perform the operation of (9x + 9) + (-9x^2 - 8x + 6)

To perform the operation, we need to simplify the expression:

(9x + 9) + (-9x^2 - 8x + 6)

First, combine like terms for the x variable:
9x - 9x^2 - 8x

Next, combine the constant terms:
9 + 6

The simplified expression is:
-9x^2 + x + 15