Answer:
He would get an adding amount to 20
Its simple, just divide 25,000 (his total amount) bc your trying to find how much cards he can buy with his total amount. This would mean 25,000 divided by 1,200 meaning 20. He would have a few more dollars but it would be enough to get a 21'th card. This mean he is stuck with 20 as his amount of cards.