Question 1180714
let father's age be {{{f}}} and son's age {{{s}}}

if a  father is {{{3}}} times older than his son, we have

{{{f=3s}}} ....eq.1


if both their ages add up to {{{54}}}, we have

{{{f+s=54}}} ....eq.2

substitute {{{f}}} from eq.1

{{{3s+s=54}}} 

{{{4s=54}}} 

{{{s=13.5}}} or {{{13}}} and {{{1/2}}}


then {{{f=3*13.5}}} =>{{{f=40.5}}} or {{{40}}} and {{{1/2}}}





 their ages are:

father is {{{40}}} and {{{1/2}}} years old
son is {{{13}}} and {{{1/2}}} years old