Our answer is 48 - 18s.

We are asked to simplify this:
-6(-8 + 3s)
In order to simplify this we need to distribute -6:
-6 * (-8) + (-6) * 3s
48 - 18s
our answer is 48 - 18s
NOTE
This property is known as the distributive property: a(b + c) = ab + ac.