The given function is $g(x) = 15 - 8x$, and you are asked to find the value of $g(-6)$.

We can do this by substituting $x = -6$ into the function:

$g(-6) = 15 - 8(-6)$

Now, calculate the result:

$g(-6) = 15 + 48 = 63$

So, the value of $g(-6)$ is 63, which corresponds to option D.

Would you like more details, or do you have any questions?

Here are 5 related questions for further practice:

1. What is $g(2)$ for the function $g(x) = 15 - 8x$?
2. What is the slope of the function $g(x) = 15 - 8x$?
3. If $g(x) = 0$, what is the value of $x$?
4. How would you graph $g(x) = 15 - 8x$?
5. Can you find the inverse of the function $g(x) = 15 - 8x$?

Tip: When dealing with linear functions like this, substituting values into the formula is straightforward, but always watch for negative signs!