(8x^3 + 6x^2 + 9) - (5x^2 + 3) + (7x^3 - 4x^2)

(8x^3 + 6x^2 + 9) - (5x^2 + 3) + (7x^3 - 4x^2)

8x^3 + 6x^2 + 9- 5x^2 - 3 + 7x^3 - 4x^2

8x^3+ 7x^3 + 6x^2- 5x^2- 4x^2 - 3 + 9

15x^3 - 3x^2 +6