Question 531715
M = Mavis' age
B = Brother's age
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M = B+5
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Five years ago...
M-5
B-5
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Mavis was twice her brother's age.
(M-5) = 2(B-5)
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Substitute M = B+5
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(B+5-5) = 2B-10
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B = 2B-10
-B = -10
B = 10
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M = B+5 = 15
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Check their ages 5 years ago.
B = 10-5 = 5
M = 15-5 = 10
M = 2*B
Correct.
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Answer: Mavis is 15 and her brother is 10 years old.
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Done.