In order to do this, all we need to do is combine like terms. The parenthesis do not matter. In order to make it easier to see, I will move the similar numbers next to each other first, and then add them.
[tex]6 x^{2} + x^{2} +5x-3-9=7 x^{2} +5x-12[/tex]
So, 7x^2 + 5x - 12 is the answer.
