Illian is at her favorite clothing store and has found a pair of pants that are on sale for 20% off the regular price. they are regularly $28. how much will be taken off the price?

There are several important information's already given in the question. Based on those given information's the answer to the question can be easily deduced.
Regular price of the pair of pants = $28
Percentage of discount on the regular price = 20%
Then
Amount of discount = (20/100) * 28 dollars
                               = 28/5 dollars
                               = 5.60 dollars
So the amount of $5.60 will be taken off the regular price. I hope the procedure is clear enough for you to understand. You can always use this method for solving similar type of problems without requiring any help from outside.