[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=6\\
x=-7
\end{cases}\implies 6=k(-7)\implies -\cfrac{6}{7}=k
\\\\\\
thus\qquad \boxed{y=-\cfrac{6}{7}x}
\\\\\\
\textit{when x = 4, what is \underline{y}?}\qquad y=-\cfrac{6}{7}(4)[/tex]
