Answer:15b^2-5b^3+24b-16
Step-by-step explanation:
(4-b)(5b^2+5b-4)
Open the brackets
20b^2+20b-16-5b^3-5b^2+4b
Collect like terms
20b^2-5b^2-5b^3+20b+4b-16
15b^2-5b^3+24b-16
