To find the slope of the line that contains the points [tex]\((-1, 8)\)[/tex] and [tex]\( (5, -4) \)[/tex], we use the slope formula:
[tex]\[
\text{slope} = \frac{y_2 - y_1}{x_2 - x_1}
\][/tex]
Substituting the coordinates of the given points into the formula where [tex]\((x_1, y_1) = (-1, 8)\)[/tex] and [tex]\((x_2, y_2) = (5, -4)\)[/tex]:
[tex]\[
\text{slope} = \frac{-4 - 8}{5 - (-1)}
\][/tex]
Simplify the expressions in the numerator and the denominator:
[tex]\[
= \frac{-4 - 8}{5 + 1}
\][/tex]
[tex]\[
= \frac{-12}{6}
\][/tex]
Now, divide [tex]\(-12\)[/tex] by [tex]\(6\)[/tex]:
[tex]\[
= -2
\][/tex]
Therefore, the slope of the line that contains the points [tex]\((-1, 8)\)[/tex] and [tex]\( (5, -4) \)[/tex] is [tex]\(-2\)[/tex].
The correct answer is [tex]\(\boxed{-2}\)[/tex].