If someone says wallahi and breaks the promise, what does he or she need to do?

This is mentioned in Surah Al-Ma'idah verse 89 where Allah says that you need to then feed 10 poor people or clothe them or you would need to free 10 slaves which isn't feasible nowadays and if you're not able to do any of the above then you would fast three days, so that's the order you would go in.