Question 644175
A man is 6 times as old as his son.  20 years later, the man will be twice as old as his son.  Find the age of the man when his son was born.
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m = 6s
m+20 = 2*(s+20)
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6s+20 = 2s + 40
s = 5
m = 30
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m - s = 25