Here is how they explain it but I still don't get how it is m/n = 2/3 and not 3/2
In problems that involve exponential expressions on both sides of the equation, it is imperative to rewrite the bases so that either the same base or the same exponent appears on both sides of the equation. Here, we can get a common base by replacing the 9 with 32.
3m3m3m = 9n
3m3m3m = (32)n
33m = 32n
Since the bases are the same, the exponents must be equal.
3m = 2n
m/n = 2/3
Can you please use the ^ symbol to show us the exponents clearly? That way we can attempt to solve the problem as it was posed to you. Other wise it can lead to many interpretations.