TeX source:

\begin{array}{rlr}\text { Average rate of change } & =\dfrac{F(6)-F(2)}{6-2} & \\ & =\dfrac{\dfrac{2}{6^{2}}-\dfrac{2}{2^{2}}}{6-2} \quad \text { Simplify. } \\ & =\dfrac{\dfrac{2}{36}-\dfrac{2}{4}}{4} & \\ & =\dfrac{-\dfrac{16}{36}}{4} \qquad \text { Combine numerator terms. } \\ & =-\dfrac{1}{9} \qquad  \text { Simplify }\end{array}