The average rate of change of a function is determined by
[tex]\frac{f(b)-f(a)}{b-a}[/tex]using the interval that you were given select the two corresponding points in the table ( 2 & 8 )
Point a (2,82)
Point b (8,16)
Replace the points into the formula
[tex]\begin{gathered} \frac{16-82}{8-2} \\ \frac{-66}{6} \\ -11 \end{gathered}[/tex]The average rate of change of the function over the inverval [2,8] will be -11