SOLUTION: Sarah is twice as old as her youngest brother. If the difference between their ages is 15 years, how old is her youngest brother?

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Question 998734: Sarah is twice as old as her youngest brother. If the difference between their ages is 15 years, how old is her youngest brother?
Found 2 solutions by stanbon, addingup:
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Sarah is twice as old as her youngest brother. If the difference between their ages is 15 years, how old is her youngest brother?
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Equations:
s = 2b
s-b = 15 yrs
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Substitute for "s" and solve for "b"::
2b - b = 15
b = 15 yrs (brother's age now)
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Cheers,
Stan H.
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Answer by addingup(3677) About Me  (Show Source):
You can put this solution on YOUR website!
If Sarah is 2times as old as her brother, then 2*brother = Sarah
S= 2b We are going to use this value for Sarah
S-b= 15 In this formula, plug in the value above for Sarah:
2b-b= 15
b= 15 And Sarah, the problem says, is twice as old:
15*2= 30 Sarah is 30. And the problem says Sarah is 15 yrs older:
30-15= 15 We have the correct answer.