Answer :
First distribute the -1 coefficient through the second set of parentheses
-5b^2-8b+9b^3+5b^2+8b now combine like terms
9b^3+(5b^2-5b^2)+(8b-8b) which gives you:
9b^3
-5b^2-8b+9b^3+5b^2+8b now combine like terms
9b^3+(5b^2-5b^2)+(8b-8b) which gives you:
9b^3