Question 803362
x years until father is three times older than his son.

{{{(45+x)/(9+x)=3}}}, ratio of their ages is three.
{{{x+45=3(x+9)}}}
{{{x+45=3x+27}}}
{{{45=2x+27}}}
{{{2x=45-27}}}
{{{2x=18}}}
{{{x=9}}}