Final answer:
The inflation rate, calculated using the percentage change formula from an original price level of 120 to a new level of 144, is found to be 20%.
Step-by-step explanation:
To calculate the inflation rate, we need to use the percentage change formula. In this case, the price level has risen from 120 to 144. First, we find the difference between the two price levels: 144 - 120 = 24. Next, we divide that difference by the original price level: 24 / 120 = 0.20. Finally, to convert this to a percentage, we multiply by 100, which gives us an inflation rate of 20%.