Answer:
(18b^2 + 9b^4) + (12b^3)
Step-by-step explanation:
(7b^2 + 3b^4) + (2b^2 + 4b^3) + (8b^3 + 6b^4 + 9b^2)
(9b^2 + 3b^4) + (4b^3) + (8b^3 + 6b^4 + 9b^2)
(18b^2 + 3b^4) + (4b^3) + (8b^3 + 6b^4)
(18b^2 + 9b^4) + (4b^3) + (8b^3)
(18b^2 + 9b^4) + (12b^3)
