Answer
$\text{Constant of variation: }
k=15
\\\text{Equation of variation: }
u=\dfrac{15}{w}
$
Work Step by Step
Since $u$ varies inversely as $w$, then $u=\dfrac{k}{w}.$ Substituting the known values of the variables, then,
\begin{array}{l}\require{cancel}
3=\dfrac{k}{5}
\\\\
15=k
\\\\
k=15
.\end{array}
Hence, the variation has the following properties:
\begin{array}{l}\require{cancel}
\text{Constant of variation: }
k=15
\\\text{Equation of variation: }
u=\dfrac{15}{w}
.\end{array}
