Is it permissible to offer the expiation for an oath (kaffarat al-yamin), which is feeding 30 needy persons, by purchasing meals (sandwich + juice + chips or biscuit) for poor female students in a school, knowing that the meal is satisfying and sufficient?

If you owe three expiations for oaths (kaffarat ayman), it is permissible for you to feed thirty needy persons (miskin) from the food mentioned, provided it is of the average quality that people in your locality consume. The feeding should be a lunch and dinner for each needy person, or two separate meals. You may feed female students two meals until the expiations are completed, but a sandwich is not considered a meal.