Final answer:
The amount of change is 5 for each number and the percent of decrease is 41.7%.
Step-by-step explanation:
The amount of change can be calculated by subtracting the new number from the original number. In this case, the original numbers are 12, 8, 7, and 3. For example, the change for the first number is 12 - 7 = 5. Similarly, the changes for the other numbers are 8 - 4 = 4, 7 - 2 = 5, and 3 - (-1) = 4.
The percent of decrease can be calculated by dividing the amount of change by the original number and multiplying by 100. For example, the percent of decrease for the first number is (5 / 12) * 100 = 41.7%. Similarly, the percent of decrease for the other numbers are (4 / 8) * 100 = 50%, (5 / 7) * 100 = 71.4%, and (4 / 3) * 100 = 133.3%.
Comparing the amounts of change, we can see that options a) and c) have the correct amounts of change, which are 5. Comparing the percents of decrease, we can see that option a) has the correct percent of 41.7%.