Which expression shows the correct first step for multiplying $2\frac{2}{3}$ by $4\frac{1}{2}$?

$2 \times 4 + \frac{2}{3} \times \frac{1}{2}$

$\frac{8}{3} \times \frac{9}{2}$

$\frac{6}{3} \times \frac{5}{2}$

To multiply $2\frac{1}{2} \times 3\frac{1}{4}$, a student calculates $(2 \times 3) + (\frac{1}{2} \times \frac{1}{4})$. Why is this method incorrect?

The whole numbers should be added, not multiplied.

This method only works for adding mixed numbers.

Mixed numbers must be converted to improper fractions before multiplying.

The fractions should be divided, not multiplied.