Answer
$r=\frac{d}{t}$, means that $r$ varies directly with $d$ and also $r$ varies inversely with $t$.
Work Step by Step
The general equation for direct variation is $y=kx$, where k is the constant of the variation.
The general equation for inverse variation is $y=\frac{k}{x}$, where k is the constant of the variation.
Here, $r=\frac{d}{t}$, means that $r$ varies directly with $d$ and also $r$ varies inversely with $t$.
As $d$ is the numerator, there will be a direct variation between $r$ and $d$, as $t$ is in the denominator, there will be an inverse variation between $r$ and $t$
As none of $d$ or $t$ is constant, there isn't any constant in these variations.
Therefore we can say that the speed varies directly with the distance traveled and varies inversely with the time needed.