Given the data:
12,3,5,9,7,x,9,4

if the range is 9, given an example of a. number that could not be.

Hi!

First let's put the numbers from least to greatest. 

(just put x anywhere)
3, 4, 5, 7, 9, 9, 12, x

So right now (excluding x) the range is 9. So x cannot be higher than 12 or lower than 3.

Just pick a number that is higher than 12, and lower than 3, and that's your answer (if that's what you're asking for)! 

Hope this helps! :)