Tina is finding the quotient of (15x^2+12x^2-9x) / 3x=-5x+4-3/x. Is she correct? If not, what changes should be made?

To calculate for the quotient when the first mathematical expression (15x² + 12x² - 9x) is divided by the second one (3x), Tina should have opted to simplify first the first expression into 27x² - 9x. Dividing each of the terms by the second expression will yield an answer of,

quotient = 9x - 3