To simplify the expression $-6(a + 8)$, apply the distributive property. This property states that $a(b + c) = ab + ac$.

So, distribute $-6$ to both terms inside the parentheses:

$-6(a + 8) = -6 \cdot a + (-6) \cdot 8$

Simplifying the terms:

$-6a - 48$

Thus, the simplified expression is:

$-6a - 48$

Would you like further details or explanations on any part of this?

Here are 5 related questions to explore further:

1. How do you factor expressions like $-6a - 48$?
2. What are the properties of distribution in algebra?
3. How do you solve linear equations with expressions like this one?
4. What happens when you distribute a positive number instead of a negative?
5. How would you simplify an expression with multiple variables?

Tip: Always watch out for signs when distributing negative numbers to avoid mistakes!