[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}\\\\
-------------------------------\\\\
\begin{cases}
y=27\\
x=3
\end{cases}\implies 27=k3\implies \cfrac{27}{3}=k\implies 9=k[/tex]
