An input/output table lists the inputs and outputs for a given equation or rule. You pick the inputs and apply the rule to obtain the corresponding outputs. For your rule "add 8", which is the same as the equation "t+8 = p", we can pick some input values that we want to work with. For no particular reason, we can choose input values of -2, -1, 0, 1, 2, 3. We could also choose 10, -20, 48, 92 if we wanted to. After we choose the input values that we are interested in, we apply the rule. For input -2, when we "add 8", we get 6. For input -1, when we "add 8", we get 7. Note that we increased the input by 1 and the output increased by 1. For input 0, when we "add 8", we get 8. For input 1, when we "add 8", we get 9. And so on. The results can be put in an input/output table. Input (t) Output (p=t+8) -2 6 -1 7 0 8 1 9 2 10 3 11