[tex]\bf slope = {{ m}}= \cfrac{rise}{run} \implies
\cfrac{{{ f(x_2)}}-{{ f(x_1)}}}{{{ x_2}}-{{ x_1}}}\impliedby
\begin{array}{llll}
average\ rate\\
of\ change
\end{array}\\\\
-------------------------------\\\\
f(x)= 300-16t \qquad
\begin{cases}
x_1=0\\
x_2=3
\end{cases}\implies \cfrac{f(3)-f(0)}{3-0}
\\\\\\
\cfrac{[300-16(3)]~~-~~[300-16(0)]}{3}\implies \cfrac{[300-48]~-~[300]}{3}
\\\\\\
\cfrac{252-300}{3}\implies -\cfrac{48}{3}\implies -\cfrac{16}{1}\implies -16[/tex]
is a negative rate, because the object is falling down, at 16 feet every passing second.
