[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} \\\\[-0.35em] \rule{34em}{0.25pt}\\\\ \stackrel{\textit{\underline{v}olume varies directly with \underline{l}ength}}{V=kL}\qquad \textit{we also know that } \begin{cases} L=30\\ k=24 \end{cases} \\\\\\ V=(24)(30)\implies V=720[/tex]
