#### Answer

$\frac{5}{4}$

#### Work Step by Step

We need to isolate y. We start by adding 5x to both sides to isolate $y$ and its coefficient. Then, we divide both sides by 4 to fully isolate $y$.
We have:
$4y=5x
\\y=\frac{5x}{4}
\\y=\frac{5}{4}x$
In a direct variation $y=kx$, the constant of variation is $k$, so the constant of variation is $\frac{5}{4}$.