Let p be the percent decrease in the price of a DVD recorder that is marked down from $500 to $400. Which proportion can be used to compute p?

A. $500-$400/$400=p/100

B. $500-$400/$500=p/100

C. $400-$500/$500=p/100

D. $400-$500/$400=p/100

The correct answer is C. $400-$500/$500=p/100.

The formula for percent change is as follows.

New - Old / Old = Percent change.

With 500 being the old score, we would look for it to be subtracted and on the bottom. C is the only option that has that.