6. -9r^3 + 11r +3 the degree is 2
7. b^3 + b^2 + 3 the degree is 3
8. 8t^2 + 3 the degree is 2
9. 4n^5 + n the degree is 5 (i'm pretty sure the two n^3 cancel out but don't take my word for it)
10. 6x +8 the degree is 1 (i'm pretty sure the two 7x^2 cancel out but don't take my word for it)
11. Not sure
12. 2v^3 - v + 8 - v^3 + v - 3 would simplify to:
v^3 +5
13. 6s^4 + 7s^2 + 7 + 8s^4 - 11s^2 + 9s would simplify to:
14s^4 - 4s^2 + 9s + 7
14. 4h^3 + 3h + 1 +5h^3 - 6h + 2 would simplify to:
9h^3 -3h + 3
15. 8z^3 - 3z^2 - 7 - z^3 + z^2 - 9 would simplify to:
7z^3 - 2z^2 - 16