Step-by-step explanation:
It might be easier thinking of "rate of change" as the slope. Since you'll be finding a slope, then, use the formula [tex]m=\frac{y_2-y_1}{x_2-x_1}[/tex] and substitute the values.
[tex]m=\frac{y_2-y_1}{x_2-x_1}\\m=\frac{20-12}{8-6}\\m=\frac{8}{2} \\m=4[/tex]
Answer:
[tex]m=\frac{4}{1}[/tex] or [tex]m=4[/tex]