First, distribute the negative one signs.
8x^5 +6x^3 -2x^2 +10x + (-1)(9x^5 -x^3 -13x^2 +4)
By multiplying -1 by 9x^5, -x^3, -13x^2, and 4. It will lead to this:
8x^5 +6x^3 -2x^2 +10x -9x^5 +x^3 +13x^2 -4
You then combine the like terms.
(8x^5 -9x^5) + (6x^3 +x^3) + (-2x^2 +13x^2) + (10x) + (-4)
This leads to the answer.
Answer: -x^5 +7x^3 +11x^2 +10x -4