What is the easiest way to withdraw funds from an RFID card to an Arduino?

Question

Arduino

It is required to organize a small card system for 5-10 attractions.
Simple, based on Arduino and RFID. An accounting system is not required.
1 - The client buys a card at the checkout and puts 200 rubles on it
2 - Approaches the attraction, applies the card, a certain amount is debited from the card (each attraction has its own).
3 - The reader gives a signal to turn on the attraction.
1 - How to put money on the card?
2 - How to cheat on the attraction?
3 - Well, it seems to be clear here.
Maybe someone will suggest an option. I will be very grateful :)

Answer 1

A win-win way: dance from the card as an identifier, and store the amounts centrally on a secure server. Then at least the clones of the cards will not be scary.
And without centralization, there will be something like old metro tickets with a magnetic stripe: through various manipulations, people completely sold "eternal" tickets - the reduced number of trips was not recorded on them -)

Answer 2

threw a hundred machine read the amount of money deducted the cost of the game and wrote back.
But it is more correct and safer to store the card number and the amount of money on it on the server. The machine connects to the server and reports how much it debits from the card.