[tex]\bf slope = {{ m}}= \cfrac{rise}{run} \implies
\cfrac{{{ h(t_2)}}-{{ h(t_1)}}}{{{ t_2}}-{{ t_1}}}\impliedby
\begin{array}{llll}
average\ rate\\
of\ change
\end{array}
\\\\\\
h(t)=300-16t^2\quad
\begin{cases}
t_1=0\\
t_2=3
\end{cases}\implies \cfrac{h(3)-h(0)}{3-0}\implies \cfrac{h(3)-h(0)}{3}[/tex]