Answer:
-4x-13
Step-by-step explanation:
To figure out the sum, you have to add like terms.
This is how it would look like:

Well first go to 'Add Attachments' when your asking a question.
Click whatever file/photo that you wanna show us, and click done.
See?
Ta da~
(6x^3y^5)2
12x^3y^5
Explanation:
Because there is no addition or subtraction between 6x^3 and y^5, they are a part of ONE term so you don't multiply each of them separately.
Best of luck