The present ages of a father and his son add up to 55 years
MATHEMATICS · Single correct · AoPS · Mathematics · One-Variable Linear Equations · One-Variable Linear Equations
Problem
The present ages of a father and his son add up to 55 years. Five years ago, the father's age was four times the son's age at that time. What is the son's present age?
(a) 10 years
(b) 15 years
(c) 14 years
(d) 12 years