[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}\\\\
-------------------------------\\\\
\stackrel{\textit{\underline{c}osts of pineapples is proportional to the \underline{a}mount of pineapples}}{c=ka}
\\\\\\
\textit{we also know that }
\begin{cases}
a=2\\
c=6
\end{cases}\implies 6=k2\implies \cfrac{6}{2}=k\implies 3=k[/tex]
