Answer:
3/2
Step-by-step explanation:
To find the rate of change
f(x2) - f(x1)
------------------ = rate of change
x2-x1
Looking at the graph
f(15) = 12
f(9) = 3
Substituting this into the equation
12-3
---------
15-9
9
------
6
3/2
The rate of change is 3/2
