[tex]\bf \qquad \qquad \textit{direct proportional variation}\\\\
\textit{\underline{y} varies directly with \underline{x}}\qquad \qquad y=kx\impliedby
\begin{array}{llll}
k=constant\ of\\
\qquad variation
\end{array}\\\\
-------------------------------[/tex]
[tex]\bf \textit{money varies directly with hourly rate of pay}\qquad \stackrel{money}{m}=k\stackrel{hour~pay}{h}
\\\\\\
\textit{we also know that }
\begin{cases}
m=168\\
h=8
\end{cases}\implies 168=k8\implies \cfrac{168}{8}=k
\\\\\\
21=k\qquad therefore\qquad \boxed{m=21h}
\\\\\\
\textit{now, when h = 6, what is \underline{m}?}\qquad m=21(6)[/tex]
