A man lived a fourth of his life as a boy, a fifth as a young man, and a third as an adult. Then he spend 13 years in his old age. How old was he when he died?

1 Answer
Jul 7, 2018

See explanation.

Explanation:

If we denote the total time the man lived as #x#, we get:

  • as a boy he spent #x/4# years,

  • as a young man : #x/5#

  • as an adult: #x/3#

  • in his old age: #13# years.

All the above expressions sum up to the man's total age, so that leads to an equation:

#x/4+x/5+x/3+13=x#

#x-x/4-x/5-x/3=13#

#(60x-15x-12x-20x)/60=13#

#13/60x=13#

#x=60#

Answer:

The man lived for #60# years.