if y varies directly with x and y=10 when x=5, what is the value of k?

[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}\\\\ -------------------------------\\\\ \textit{we know that } \begin{cases} y=10\\ x=5 \end{cases}\quad 10=k5\implies \cfrac{10}{5}=k\implies 2=k[/tex]