So, we want to find the average rate of change of:

From 3 to 7.
First, remember that the average rate of change of a function f(x) from a to b, can be found using the following formula:

Where:
f(b) is the value of the function at the point b.
f(a) is the value of the function at the point a.
b is the final point
a is the initial point.
In our problem, we're given that:

Now, let's just replace these values in the previous formula:

Therefore, the average rate of change is -30.
exercise:
Find the average rate of change of f(x):

From 4 to 6.