How old is Tony in Bless Me, Ultima?

Excuse me, but I'm curious about something I read in the book "Bless Me, Ultima." Can you please clarify for me how old Tony is in the story? I'm having a bit of trouble pinpointing his exact age, and it's important for my understanding of his character development and the events that unfold. Is there a specific mention of his age or can we infer it from his actions and the context of the story? Thank you for your help!