SOLUTION: the difference between Maria's age and her sister's age is 3. If Maria is seven years younger than twice her sister's age, how old is Maria?

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Question 582180: the difference between Maria's age and her sister's age is 3. If Maria is seven years younger than twice her sister's age, how old is Maria?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
the difference between Maria's age and her sister's age is 3. If Maria is seven years younger than twice her sister's age, how old is Maria?
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Equations:
m - s = 3
m = 2s-7
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Sustitute for "m" and solve for "s":
2s-7-s = 3
s = 10 yrs (sister/s age)
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Solve for "m":
m = 2s-7
m = 2*10-7
m = 13 yrs (Maria's age)
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Cheers,
Stan H.