Use Euler;s Theorem to find all incongruent solutions of each congruence below.

9x is congruent to 21 mod 25.

OK, I know this is an easy computational but my anwser still does not math the books. can someone spot the error:

1) i found the inverse of 9 modulo 25 to be 9^22. multiply both side and get

2) x is congruent to 9^22 times 21 mod 25

3) so then i get x is congruent to 7 mod 25.

and i get the anwser of 4.

I dont know where are my mistakes?