Direct variation is of the form y=kx
2x-4y=0 subtract 2x from both sides
-4y=-2x divide both sides by -4
y=x/2 or to be clear:
y=(1/2)x
So there is a constant of variation k=1/2 of the form y=kx, so this equation is a direct variation.
*note, it is called a direct variation because as the independent variable increases/decreases, the independent variable increases/decreases by the same factor...
