How to subtract the quantity of any element in a map

I have tried the Store and inventory system but I have a problem when I want to see the current item and get its price and subtract from player money I can’t

Please If someone has time to quickly look at the link to understand me well I would be very grateful :pray::pray::heart::heart::heart::heart:

In the video they start explaining at 1:04. Are you not able to follow or where are you stuck?

No, I finished the PlayList, But When I Want To Get Current Slot Price Or Name I Can’t Please Help :pray:

Exactly :