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

Direct variation is of the form
y= mx

2x-4y = 0
2x = 4y
4y = 2x
y = 2/4 x
y =(1/2)x
which is indeed of the form y = mx
Hence, the equation does represent direct variation.

in y= mx,
the constant of variation is m
so in y = (1/2)x
the constant of variation is 1/2

Num of plants = (original#ofplants)*(1.6)^t