well, hmmm let's see, when x = 7, y is hmmm way up above, is 19
and when x = 11, y is 11 also
so, we have the points of ( 7 , 19 ) and ( 11 , 11 )
thus [tex]\bf \begin{array}{lllll}
&x_1&y_1&x_2&y_2\\
% (a,b)
&({{ 7}}\quad ,&{{ 19}})\quad
% (c,d)
&({{ 11}}\quad ,&{{ 11}})
\end{array}
\\\\\\
% slope = m
slope = {{ m}}= \cfrac{rise}{run} \implies
\cfrac{{{ y_2}}-{{ y_1}}}{{{ x_2}}-{{ x_1}}}\implies \cfrac{11-19}{11-7}\impliedby
\begin{array}{llll}
average\ rate\\
of\ change
\end{array}[/tex]
