Answer:
-1;undefined;1;0
Explanation:
The first one (-9/9), can also be written as - 9/9 = - 1.
The second one (9/0), is undefined because every single term even 0 itself, if you divide it by 0, it'll be undefined!
The third one, we see we have division, and whenever we have division or multiplication and also 2 negative signs, they cancel each other, as you're left with 9/9=1.
The fourth one, whenever you have 0 at the numerator, no matter the denominator(only matters when it's =0, but that's undefined), the result will always be 0 !