[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}\\\\
-------------------------------\\\\
\textit{we also know that }
\begin{cases}
y=216\\
x=2
\end{cases}\implies 216=k2\implies \cfrac{216}{2}=k
\\\\\\
108=k\qquad therefore\qquad \boxed{y=108x}
\\\\\\
\textit{when x = 7, what is \underline{y}?}\qquad y=108(7)[/tex]
