[tex]\bf \qquad \qquad \textit{direct proportional variation} \\\\ \textit{\underline{y} varies directly with \underline{x}}\qquad \qquad \stackrel{\textit{constant of variation}}{y=\stackrel{\downarrow }{k}x~\hfill } \\\\[-0.35em] ~\dotfill\\\\ \textit{we know that } \begin{cases} x = 0.14\\ y = 0.7 \end{cases}\implies 0.7=k(0.14)\implies \cfrac{0.7}{0.14}=k\implies 5=k \\\\\\ ~\hfill \boxed{y = 5x}\qquad \qquad \boxed{\cfrac{y}{5}=x}~\hfill[/tex]
Check the picture below.
