A mother is 21 years older than her son, and in 6 years time the son will be one fifth of her age.

Where is the father?

let the mother's age = x
the son's age = y

now x = y + 21
after six years (x+6)/5 = y + 6

putting both equations together we get
y + 21 = 5y + 24
y = - 3/4 years
which means (-9 months) , so the mother is not pregnant yet and so there is no father
QED :)

Posted by A on 2002-11-27 00:17:31