Question

R varies directly as s. Find r when s=4 and k=2

Answer 1

$\bf \begin{array}{cccccclllll} \textit{something}&&\textit{varies directly to}&&\textit{something else}\\ \quad \\ \textit{something}&=&{{ \textit{some value}}}&\cdot &\textit{something else}\\ \quad \\ y&=&{{ k}}&\cdot&x \\ && y={{ k }}x \end{array}\\\\ -------------------------------\\\\ thus\implies r=ks\qquad \begin{cases} k=2\\ \uparrow \\ constant\ of\\ variation\\ s=4 \end{cases}\implies r=2\cdot 4$