#### Answer

$k=\frac{1}{6}$, $y=\frac{1}{6}x$

#### Work Step by Step

If y varies directly as x, we know that the variables x and y can be related by the function $y=kx$, where k is the constant of proportionality.
If $y=5$ when $x=30$, then we know that $5=30k$. Divide both sides by 30.
$k=\frac{5}{30}=\frac{1}{6}$
Therefore, the constant of variation is $k=\frac{1}{6}$ and the direct variation equation is $y=\frac{1}{6}x$.