To determine the rule for generating the next term in the sequence 23, 19.5, 16, 12.5, we should analyze how the sequence is progressing.
- From 23 to 19.5, the change is 19.5 - 23 = -3.5.
- From 19.5 to 16, the change is 16 - 19.5 = -3.5.
- From 16 to 12.5, the change is 12.5 - 16 = -3.5.
In each step, we are consistently subtracting 3.5. This indicates that we are adding a common difference of -3.5 to each term to arrive at the next term.
Therefore, the correct answer is:
Add the common difference of -3.5.