#### Answer

$k=189$, $y=\frac{189}{x}$

#### Work Step by Step

If y varies inversely as x, we know that the variables x and y can be related by the function $y=\frac{k}{x}$, where k is the constant of proportionality.
If $y=63$ when $x=3$, then we know that $63=\frac{k}{3}$. Multiply both sides by 3.
$k=63\times3=189$
Therefore, the constant of variation is $k=189$ and the inverse variation equation is $y=\frac{189}{x}$.