Answer:
(c) 9
Step-by-step explanation:
You can't have a repeated x-value in a function.
8 is taken by (8, 7)
7 is taken by (7,-6)
-4 is taken by (-4, 5)
9 is the only number that is not taken by any other point yet.
Remember that for a relationship to be a function it can't have repeated x-values. However, it doesn't matter to have the same x and y values!
Hope this helped!