Answer
variation constant$=k=90$
equation of variation: $y=\frac{90}{x}$
Work Step by Step
$y$ varies inversely as $x$ so the variation is inverse.
The equation of an inverse variation is of the form $y=\frac{k}{x}$ where $k$ is the constant of variation.
To find the value of $k$ substitute the given values of $x$ and $y$ into $y=\frac{k}{x}$ to obtain:
$$y=\frac{k}{x}
\\9=\frac{k}{10}
\\9(10) = k
\\90=k$$
Thus, the equation of the variation is $y=\frac{90}{x}$.
