Abook costs $25 .marilyn bought the book during a sale with 15% discount. how much did she pay for the book

Original cost of the book = $25
Percentage of discount got by Marilyn while buying the book = 15%
Amount of discount got by Marilyn while buying the book =  (15/100) * 25
                                                                                            = 375/100
                                                                                            = 3.75 dollars
So
The amount paid by Marilyn for buying the book = (25 - 3.75) dollars
                                                                              = 21.25 dollars
So the total amount paid by Marilyn for buying the book is $21.25. I hope the procedure for doing this problem is clear to you.