Question 1069228
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The equations are

M + 2S = 90,     (1)   ("THE PRESENT AVERAGE AGE OF A MAN AND HIS TWIN SON IS 30 YEARS" is the same as to say M + 2S = 90)
M/S = 5/2        (2)

Equivalently

M + 2S = 90,
M = {{{(5/2)*S}}}.

--->  {{{(5/2)*S + 2S}}} = 90  --->  5S + 4S = 180  --->  9S = 90  --->  S = 20  --->  M = {{{20*(5/2)}}} = 50.


<U>Answer</U>.  Man is 50 years now. The sons (the twins) are 20 years old each.
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