Acomputer monitor is regularly priced at $320. during a two day sale the price was decreased to$240. which of the following is the percentage decrease of the monitors price during the sale?

In the question there are several information's worth taking note of. based on the given information's the required answer can be easily deduced. It is already given that the regular price of the computer monitor is $320. It is also given that during a two day sale the monitor price was decreased to $ 240. It is required to find the percentage decrease in the price of the monitor during the sale period.
Difference in price of the monitor = (320 - 240) dollars
                                                      = 80 dollars.
Percentage of price decrease of the monitors = (80/320) * 100
                                                                           = 100/4
                                                                           = 25
So the price of the computer monitor was reduced by 25%.

What's the denominator