SOLUTION: Matthew is 3 times as old as Jenny. In 7 years, he will be twice as old as she will be then. How old is each now?

Question 357656: Matthew is 3 times as old as Jenny. In 7 years, he will be twice as old as she will be then. How old is each now?
Found 2 solutions by stanbon, robertb:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Matthew is 3 times as old as Jenny. In 7 years, he will be twice as old as she will be then. How old is each now?
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Equations:
m = 3j
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m+7 = 2(j+7)
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Substitute for "m" and solve for "j":
3j+7 = 2j+14
j = 7 (Jenny's age now)
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Since m = 3j, m = 21 (Matthew's age now)
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Cheers,
Stan H.
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Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
m = 3j,
m+7 = 2(j+7). Substituting the first equation into the 2nd, we get
3j+7 = 2j+14, and so
j = 7, and m = 21.

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