what is the correct equation

Answer: y = 0.4x
In fraction form, this is y = (2/5)x
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Explanation:
For each row, divide the y over x values
We end up with the same thing each time.
Since y/x = 0.4, this rearranges to y = 0.4x
Alternatively, you can write the equation as y = (2/5)x because 2/5 = 0.4