1. "Alas-tres singkwenta ng hapon" (formal)
* Alas-tres: Three o'clock
* Singkwenta: Fifty
* ng hapon: in the afternoon
2. "Tres singkwenta ng hapon" (more casual)
* Tres: Three
* Singkwenta: Fifty
* ng hapon: in the afternoon
Both are correct, but the first one is more formal and used in situations where you want to be respectful. The second one is more casual and can be used in everyday conversations.