[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=0.6\\
x=0.5
\end{cases}\implies 0.6=k0.5\implies \cfrac{0.6}{0.5}=k
\\\\\\
1.2=k\qquad therefore\qquad \boxed{y=1.2x}
\\\\\\
\textit{when x = 15, what is \underline{y}?}\qquad y=1.2(15) [/tex]
