Does the equation represent a direct variation? if so, find the constant of variation. 2x - 4y = 0

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...