Respuesta :

To be a proportional relationship betwen x and y, there has to be only this two variables and a number multiplying one or both of them:

[tex]a\cdot y=b\cdot x[/tex]

Let a and b be constants. So, from your question, there's only one that meets the requeriments:

[tex]y=\frac{1}{5}x[/tex]

The other options have another constant (number) in addition, so the relationship is not proportional anymore.

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