To determine where the function $f$ is decreasing, we need to identify the intervals on the $x$-axis where the graph is sloping downwards as $x$ increases.

Looking at the graph, $f$ appears to be decreasing in the following intervals:

1. From $x = -7$ to $x = -4$, the graph slopes downward.
2. From $x = -1$ to $x = 2$, the graph also decreases.

Therefore, the intervals where the function $f$ is decreasing are: $(-7, -4) \text{ and } (-1, 2)$

Would you like further explanation on how to interpret these intervals or any other aspect?

Here are 5 related questions for further practice:

1. How do you determine where a function is increasing on a graph?
2. What is the significance of turning points in identifying increasing and decreasing intervals?
3. How can you identify intervals of positive and negative values for $f(x)$?
4. How does the concept of the derivative relate to increasing and decreasing intervals?
5. What is the role of concavity in understanding the behavior of a function's graph?

Tip: When analyzing graphs for increasing or decreasing behavior, always look for the slopes of the curve between critical points.