Question 621995
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Hi,
a father is 60 years old and son is half his age or {{{30}}}
how old was the boy when ({{{highlight(x)}}} years ago) the {{{father}}} was four times his age?
  4(30 -x) =  60-x
    60 = 3x
   x = 20, number of years ago.  Son was 10 at that time. (and the father 40)