SOLUTION: Part 1: Bri's brother is 3 years younger then her and her sister is twice as old as her. The sum of all three of their ages is 45. How old is Bri? Part 2: How old will Bri's

Question 745299: Part 1:
Bri's brother is 3 years younger then her and her sister is twice as old as her. The sum of all three of their ages is 45. How old is Bri?
Part 2:
How old will Bri's brother be when her sister is twice as old as her brother?
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Bri's brother is 3 years younger then her and her sister is twice as old as her. The sum of all three of their ages is 45. How old is Bri?
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Equations:
b = B-3
s = 2B
b + B + s = 45
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Substitute for "b" and for "s" and solve for "B":
B-3 + B + 2B = 45
4B = 48
B = 12 yrs (Bri's age now)
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Part 2:
How old will Bri's brother be when her sister is twice as old as her brother?
If s = 2b then 2B = 2(B-3)
But that is a contradiction: 2B = 2B-6
Her sister cannot be twice as old as her brother.
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Cheers,
Stan H.

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