Answer :

it is not a mixed number because if you put the same number of the numerator on the denominator it would be a mixed number (1)

you cannot express 9/9 as a mixed number becasue 9 divided by 9 is 1 wth nothing left over, tecnically you can add 0/(any number) and it would remain true becasue 0 OVER anything is 0. [tex] \frac{9}{9} \\ 1 \frac{0}{any_-number} \\ 1[/tex]