The input is the x value. The output is the y value. The question is asking for a function which will give you the output when the x value is plugged in. The input is increasing by 1 each time. The output is decreasing by 3 each time. -3÷1=-3. Therefore, x is going to be multiplied by -3. However, -3x does not equal the Y-value so one must determine if something is being added. -3×1=-3 =/= -1. However, (-3×1)+2=-1. -3x+2 is a possible function of Y. To check, one can plug in the rest of the X values to determine if the answer will be equal to the Y value given in the table.
Therefore: Y=-3x+2.