Question 891711
A mother is 21 years older than her son. 
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Let the son be S years old
Then the mother is S+21
</pre>
6 years from now exactly, the mother will be exactly 5 times
as old as the child. 
<pre>
S+21+6 = 5(S+6)
  S+27 = 5S+30
    -3 = 4S
  -3/4 = S  

So the son is negative three-fourths of a year old, which means
he has not been born yet.  Since three fourths of a year
before he is born is 9 months before he is born, he is just
being conceived.
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Where's the child's dad?
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Having sex with his mother.  LOL

Edwin