Question 890563: a man is 30 years older than his son . in 12 years the man will be 3 times older than his son .find their present age.
Answer by JulietG(1812)   (Show Source):
You can put this solution on YOUR website! M = S + 30
M + 12 = 3(S + 12)
Substitute the value of M from the first equation into the second.
M + 12 = 3(S+12)
(S+30) + 12 = 3(S+12)
Distribute/Add
S + 42 = 3S + 36
Subtract S from each side
42 = 2S + 36
Subtract 36 from each side
6 = 2S
Divide each side by 2
3 = S
The son is 3, therefore the man is 33
In 12 years, the son will be 15, and the man will be 45 -- 3x the son's age.
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