Well 50's in like....Red XIII years, but in human years he's the youngest guy in the party with Yuffie.
Actually Red Is 16 in red years and 50 in human years, otherwise he wouldn't be alive (SPOILER) 500 years later
And who is Mukki
No, red is 16 in human years, which is why he was being treated like a child by his "grand father" in which his arguement was, but I'm 48 (or forty six). To which his grandfather replied, Not in human years. or something of that sort.