[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}
\\\\[-0.35em]
\rule{34em}{0.25pt}[/tex]
[tex]\bf \textit{we also know that }
\begin{cases}
y=5\\
x=6
\end{cases}\implies 5=k6\implies \cfrac{5}{6}=k
\\\\\\
therefore\qquad \boxed{y=\cfrac{5}{6}x}
\\\\\\
\textit{when x = 5, what is \underline{y}?}\qquad y=\cfrac{5}{6}(5)\implies y=\cfrac{25}{6}\implies y=4\frac{1}{6}[/tex]
