The student is incorrectly applying the fundamentals laws of fractions because the theorem is only true for products
Here, we want to correct a calculation error by a student
The calculation error is;

This is mathematically incorrect and we want to state why it is
If the evaluation was as follows;

This would have been correct
The reason it is wrong is that it can only work for a product for the same value for each of the numerator and denominator
The answer is thus;
The student is incorrectly applying the fundamentals laws of fractions because the theorem is only true for products