If it's for a graph then I believe you just find the slope which you can do by taking two points and plugging them into this equation y-y
/
X-X
Example: (2, 4) and (6, 7) the first number is always x and the second is always y so if you plug those in the equation would look like this....
4-7
/
2-6
That would end up being
3
- ---- aka the rate of change
4
P.s. The slash and the four dotted lines together means division. Hope this helps