Melody has two coins that equal 15 cents. What are the two coins if one of them is not a nickel?

I need to start with some assumptions here.

First, I'm assuming that this is U.S. coins, not Euros, etc.

Second, I'm assuming that we are talking about the face value of the coins, not their value to collectors. Thus, a penny is worth one cent -- even if it is an old and rare penny and so worth more than one cent to collectors.

If both those assumptions are correct, then you can't get there from here. There are no two US coins that add up to 15 cents other than one dime and one nickel. Of course, you could have a dime and 5 pennies, but that would be six coins.

My guess is that there is some trick that involves a quarter, a dime and subtraction. For example, if Melody owed someone 15 cents so she gave them a quarter and they gave her a dime in change. The exchange of the two coins would equal her 15 cent debt.