First off,
If 20% of the original price is $15 you basically need to find the rest of the percentage.
100% - 20% = 80%
Next, you need to divide $15 by %80.
= $18.75
You can test to see if this is right by multiplying $18.75 by %20. Which should give you, 3.75( the amount of discount). $18.75 - $3.75 = $15.
Answer: Regular price was $18.75.
