Rate of Change:
The rate of change is the rate at which the y value increases or decreases, with respect to the x value.
The expression that represents rate of change is:

To find the rate of change of a graphed line you must begin at the starting point, or y intercept, of the graph. From this point, move to the right one unit, then count the number of units straight up you must go up or down until you touch the graphed line. The number of units you moved upward or downward is the number that goes on the top part of the equation, and the number of units you moved to the right (one) is the number that goes on the bottom of the equation. You have now found the rate of change function for the sloped line. To check your equation, repeat this step from your ending point on the line and continue the process.

A second way to find the rate of change of a graph, without already having a line, is to pick two sets of data points, or two sets of corresponding data, and to put these data into the equation .
Example:

Slope:
The slope of a line is the incline, or direction and steepness, of a line along the graph from left to right. It is the rate of change.