The 1st, 2nd, and 4th selections are appropriate.
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The relationship is linear (power of x is 1), so its equation is a line (with slope -4/3). Any linear relationship (where the line is not vertical) is a function.
You have to check the input and output values to see which work and which don't.
This equation is in "slope-intercept" form, where the y-intercept is 1/3. (not 1)
