Which of the following expressions is simplified correctly?

$\frac{4 + 9}{4 + 3} = \frac{9}{3}$

$\frac{4 \cdot 9}{4 \cdot 3} = \frac{9}{3}$

$\frac{9 - 4}{3 - 4} = \frac{9}{3}$

A student incorrectly simplified $\frac{7 + 5}{5}$ to be $7$. Why is this simplification incorrect?

The number 5 is a common factor.

The number 5 is a term in the numerator, not a common factor.

Addition must be done after division.

The number 7 is not divisible by 5.

Yes, because 2 can be canceled from the numerator and denominator.

No, because 2 is a term being added, not a common factor.