Given:
The points are (1,9.5), (2,12), (3,14.5), (4,17).
To find:
The rate of change in the expression.
Solution:
Clearly the value of y increasing with respect to x by a constant rate.
Formula of rate of change is

Consider the any two points from the expression (1,9.5) and (2,12).



Therefore, the rate of change is 2.5.