Diophantus of Alexandria
Diophantus is one of the brilliant Greek mathematicians born around 250 AD. His birth until death may be determined from an epitaph revealing the fact that he passed a sixth of his life in childhood, a twelfth in adolescence and a seventh more as a bachelor. Five years after he got married, a son was born to him who died four years before Diophantus at one-half his father's final age. How old was Diophantus when his son was born?