[tex]\bf \stackrel{\textit{\underline{j} and \underline{k} are inversely proportional}}{j=\cfrac{c}{k}}\qquad \textit{we also know that }
\begin{cases}
j=16\\
k=21
\end{cases}
\\\\\\
16=\cfrac{c}{21}\implies 336=c\qquad therefore\qquad\qquad \boxed{j=\cfrac{336}{k}}
\\\\\\
\textit{when k = 14, what is \underline{j}?}\qquad j=\cfrac{336}{14}[/tex]