Find each of the following sums and differences. Write your answer in simplest standard form. (Help with b and d)

Good job, you started on the right track, you just have to finish. You have to combine like terms(anything that's the same like x^3 and x^3, or like 8 and 2)      (b): 2x^3+4x^2-9x+4                                                                                              (d)6x^3-13x^2+11x+10                                                                                                  Hopefully that helps, and I'm sorry I'm bad at explaining