Answer:
6. Is this your sandwich? - Yes, this is your sandwich.
7. Is this our parking space? - Yes, this is our parking space.
8. Are these our notebooks? - Yes, these are our notebooks.
9. Did you return Amanda’s book back to the bookstore? - Yes, I returned her book back to the bookstore.
10. Does this business belong to you and me? - Yes, this business belongs to both of us.
Hope this helps!