To solve $f(5)$ for the function $f(x) = -x - 1$, follow these steps:

1. Substitute $x = 5$ into the function: $f(5) = -5 - 1$

2. Simplify the expression: $f(5) = -6$

So, $f(5) = -6$.

If you need to find the value of $5f(5)$:

3. Multiply $f(5)$ by 5: $5f(5) = 5(-6) = -30$

Therefore, $5f(5) = -30$.

Would you like more details or have any questions? Here are some related questions you might find interesting:

1. How do you find the value of $f(x)$ for different values of $x$?
2. What is the general approach to evaluating functions?
3. How would you solve $f(x) = -x - 1$ for other values like $x = -2$?
4. What is the domain and range of the function $f(x) = -x - 1$?
5. How do you graph the function $f(x) = -x - 1$?
6. What are the properties of linear functions like $f(x) = -x - 1$?
7. How do you find the inverse of the function $f(x) = -x - 1$?
8. What is the effect of multiplying a function by a constant, like $5f(x)$?

Tip: When dealing with linear functions, remember that the slope indicates how steep the line is, and the y-intercept is where the line crosses the y-axis.