How can you determine if there is a constant rate of change? What is the rate of change and what does that represent in the problem situation

There is a constant rate of change if all points or data lie on the same straight line.
Example :
As you can see, all the points are in one straight line.
Rate of change is the amount of change in the y axis with respect to the x axis.
Rate of changle is also called slope.
And note that a straight line has only 1 slope which makes the points in a line having a constant rate of change.