Respuesta :
[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{x}{5}~,~\stackrel{y}{8})\textit{ we also know that }
\begin{cases}
x=5\\
y=8
\end{cases}\implies 8=k5\implies \cfrac{8}{5}=k[/tex]
we know that
A relationship between two variables, x, and y, represent a direct variation if it can be expressed in the form [tex]\frac{y}{x}=k[/tex] or [tex]y=kx[/tex]
where
k is the constant of variation
in this problem we have
the point [tex](5,8)[/tex]
so
[tex]x=5\\y=8[/tex]
substitute
[tex]\frac{y}{x}=k[/tex]
[tex]\frac{8}{5}=k[/tex]
therefore
the answer is
[tex]k=\frac{8}{5}[/tex]