Answer:
D
Step-by-step explanation:
You would multiply the -5 and the -1 from the -5x^4 and the -x^5 this would make 5. Also the 4 and the 5 exponets, since they are exponets you need to add if multiplying so it would just be 4+5=9.
For y its just multiplying the exponets which is y^4xy^4=y^8.
Final answer if you bring everything together is 5x^9y^8 also answer D.
