[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~{{ 0}} &,&{{ 27}}~)
% (c,d)
&&(~{{ 5}} &,&{{ -8}}~)
\end{array}
\\\\\\
% slope = m
\stackrel{\stackrel{average}{rate~of~change}}{slope}= {{ m}}\implies
\cfrac{\stackrel{rise}{{{ y_2}}-{{ y_1}}}}{\stackrel{run}{{{ x_2}}-{{ x_1}}}}\implies \cfrac{-8-27}{5-0}\implies \cfrac{-35}{5}\implies -7[/tex]
well, when x = 0, namely at the very beginning, y = 27, thus, that IS the initial value.
