Answer:
[tex]72a^8b^6c^6[/tex]
Step-by-step explanation:
[tex]9a *4a^3b^5*2a^4bc^6\\72a^4a^3ab^5bc^6\\\\[/tex]
After this step, combine like terms!
[tex]72b^5a^8bc^6[/tex]
After that, apply what you know about exponents, specifically the multiplication of exponents rules...
[tex]72a^8b^6c^6[/tex]
This is your answer!