Question 1037631
Father and Son in 8+5=13 parts.
Mother and Son in 7+8=15 parts.


Father to Son ratio is  {{{8/13}}} to {{{5/13}}}.
Mother to Son ratio is {{{7/15}}} to {{{8/15}}}.  NO.  This cannot be.  The mother must be OLDER THAN her son.  Make this ratio  {{{8/7}}} instead.



Let f be father's age.
{{{f*(5/8)}}} is son's age.


If son's age is  {{{f(8/5)}}}, then use Mother to Son ratio to get Mother's age.
{{{f(5/8)(8/7)}}}---------------------this is  {{{5/7}}}