To simplify the expression $-2(z - 3)$, distribute the $-2$ across the terms inside the parentheses:

$-2(z - 3) = -2 \cdot z + (-2) \cdot (-3)$

This simplifies to:

$-2z + 6$

So, the simplified expression is:

$-2z + 6$

Do you have any questions or need further details?

---

Here are 5 related questions for practice:

1. Simplify the expression $3(x + 4)$.
2. What is the simplified form of $-5(y - 7)$?
3. Expand and simplify the expression $4(2x - 5)$.
4. Simplify the expression $6 - 2(3 + x)$.
5. How would you simplify $7(2a - 3) + 2(a + 4)$?

Tip: Always distribute the multiplication to each term inside the parentheses when simplifying expressions.