#### Answer

The constant of variation is $700$.
The inverse variation equation is $y=\frac{700}{x}$.

#### Work Step by Step

$y=\frac{k}{x}$
$y=100; x=7$
$100=\frac{k}{(7)}$
$100\times7=k$
$700=k$
The constant of variation is $700$.
The inverse variation equation is $y=\frac{700}{x}$.