Hello Elli,
When you have a variable with exponent in the numerator and same variable with exponent in the denominator, subtract the exponents (numerator exponent - denominator exponent).
If the result is positive, leave the variable with the new exponent in the numerator. If the exponent is negative, put the variable with new exponent in the denominator.
See Chris's last example.
When he subtracted 24-30, the result was -6. So he put the in the denominator.