Step-by-step explanation:

(a)
the list would be
-20, -12, -8, -1, 1, 5, 10
the other intergers would have to be greater than 1 in order to be on the correct side and cause 1 to be in the middle. They could be anything but 5 and 10 because these were already chosen.
(b)
the list would be like before
-3 was not included so one of the chosen would be -3 and the other would have to be less than -3 but not -8, -12, or -20 beacuse those were already chosen
Answer:
-5n²-8n+4
Step-by-step explanation:
Remove Parentheses :
3n²-5n+6 - 8n²-3n-2
Collect/Combine Like terms:
(3n²-8n²) + (-5n-3n) +(6-2)
Simplify:
-5n²-8n+4
12.5 is the halfway point