A price falling from 80 dollars to 60 dollars gives a percent decrease based on a difference of:

1. Percent decrease starts from the size of the drop. 2. The amount of decrease is the difference between the original amount and the final amount. 3. Here the original amount is 80 dollars and the final amount is 60 dollars. 4. The difference between them is 20 dollars. 5. That difference is then compared with the original amount. _Source: OpenStax Prealgebra 2e (CC BY 4.0), Ch 6 'Percents', sections 6.1-6.5_