How do you find the rate of change on a graph

The rate of change of a graphed function is the ratio of the change in the ordinate value to the change in the abscissa value between two points. When the plot has y on the vertical axis and x on the horizontal axis, the rate of change is
.. (change in y)/(change in x)

When the plot is of a straight line, you find the rate of change by locating two points on that line whose coordinates you can read from the graph. Then subtract the y-value of the first from that of the second to get the change ∆y. Do the same for the x-values: subtract the first from the second to get ∆x. The "rate of change" between the points you selected is
.. rate of change = (∆y)/(∆x)

If the plot goes upward from left to right, the rate of change is positive. If it goes downward left to right, the rate of change is negative.

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