What is the Shariah ruling on a Da'wah office contracting with institutions to provide free juices to pilgrims at a price of 70 halalas per package, then selling them to those who desire them for one riyal, such that the surplus goes to support the Da'wah activities of the office, while announcing that the project's proceeds are for supporting the office's activities? And how can the project be proposed in a sound manner without Shariah prohibitions?

The mentioned transaction is permissible as long as the advertisement states, "Proceeds of the project to support the Dawa (Islamic propagation) activities of the office," and the donor is aware that you profit from the transaction and that this profit will support the Dawa activities. There is no need to disclose the exact amount of profit to the donor, because their intention is to donate, not to exchange, and leniency is usually applied in matters of donations.