Answer:
The equation x+3=9 is true if and only if x=6.
Not enough information.
Explanation:
We are looking for a if and only if statement for a bioconditional.
There is only one such choice:
The equation x+3=9 is true if and only if x=6.
We only know information about the triangle's angles, and nothing about their sides. AAA (angle-angle-angle) is not enough information to conclude congruence. It is enough for proving it to be similar.