To solve this problem you must apply the proccedure shown below:
1. By definition, the rate of change of a linear function is the slope of the line and it is constant. Based on this, you must find the slope of the given function.
2. You have the equation of the line has the following form:
Where is the slope and
is the y-intercept.
3. Then, you have that the slope of the function is:
Therefore, the answer is: