The image shows a graph of a linear function $f(x)$. To find $f(-1)$, we need to determine the value of the function when $x = -1$.

By locating $x = -1$ on the horizontal axis and tracing up to where it intersects the blue line, we see that the corresponding $y$-value is $5$.

Thus, $f(-1) = 5$.

Would you like more details on how to interpret graphs, or do you have any further questions?

Here are 5 related questions to expand on this concept:

1. How do you find the slope of a line from a graph?
2. What is the equation of the line shown in the graph?
3. How would you calculate $f(x)$ for any given value of $x$?
4. What is the meaning of the y-intercept of a line?
5. How can you determine whether a function is increasing or decreasing from a graph?

Tip: When analyzing a graph, always check for key points such as intercepts and slope to better understand the function's behavior.