Is it permissible to pay a monetary fidyah instead of fasting the missed days of Ramadan, given the inability to fast all of them, and how much is the value of this fidyah?

Whoever breaks their fast in Ramadan due to a legitimate Shar'i excuse must make up the days they missed if they are able to fast. It is not permissible for them to feed the poor instead of making up the fasts, based on the Almighty's saying: (And whoever is ill or on a journey - then an equal number of other days) Al-Baqarah/185. It is permissible to separate the making up of the missed days; continuity is not required. The missed fasts of the previous Ramadan must be made up before the entry of the subsequent Ramadan.