#### Answer

The constant of variation is $0.25$.
The direct variation equation is $y=0.25x$.

#### Work Step by Step

$y=kx$
$y=0.2; x=0.8$
$0.2=k(0.8)$
$0.2\times1.25=k$
$0.25=k$
The constant of variation is $0.25$.
The direct variation equation is $y=0.25x$.