|z-7|-|z-9|, if z<7

Answer 1

Recall the definition of |x|
If z < 7 then
|z-7| = 7-z
|z-9| = 9-z
(7-z)-(9-z) = -2

Answer 2

n

Answer 3

I'm sorry, can you please provide more information or context for your question about "n"?