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

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

4r^3 - 5r^2 + 8 + 2r^2 - 6 - 3r^3 - 7r^2

4r^3- 3r^3 - 5r^2+ 2r^2- 7r^2 + 8- 6

r^3 - 10r^2 +2