Alex made 1600 bucks in 400 hours... how much did he make in 0 hours? well, he just laying on a hammock, so he did 0 dollars then.
so,
[tex]\bf \begin{array}{ccll}
\stackrel{x}{hours}&\stackrel{y}{dollars}\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
0&0\\
400&1600
\end{array}
\\\\\\
\begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~ 0 &,& 400~)
% (c,d)
&&(~ 0 &,& 1600~)
\end{array}
\\\\\\
% slope = m
slope = m\implies
\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{1600-0}{400-0}\implies \cfrac{1600}{400}\implies \cfrac{4}{1}\implies 4[/tex]
now, let's take a peek at g(x)'s slope,
[tex]\bf \begin{array}{ccll}
x&g(x)\\
\text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\
\underline{1}&\underline{-8}\\
5&12\\
\underline{9}&\underline{32}
\end{array}\impliedby \textit{let's pick two points}[/tex]
[tex]\bf \begin{array}{ccccccccc}
&&x_1&&y_1&&x_2&&y_2\\
% (a,b)
&&(~ 1 &,& -8~)
% (c,d)
&&(~ 9 &,& 32~)
\end{array}
\\\\\\
% slope = m
slope = m\implies
\cfrac{\stackrel{rise}{ y_2- y_1}}{\stackrel{run}{ x_2- x_1}}\implies \cfrac{32-(-8)}{2-1}\implies \cfrac{32+8}{9-1}\\\\\\ \cfrac{40}{8}\implies 5[/tex]
well, all we can say is that, they differ.