Question 549169
J = Jim's age
A = Amy's age
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Jim is 3 times as old as Amy.
J = 3*A
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Four years ago:
J-4 = Jim's age
A-4 = Amy's age
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Four years ago, Jim was 7 times as old as Amy.
J-4 = 7*(A-4)
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Substitute J=3*A
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3A-4 = 7A - 28
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3A -7A = -28 + 4
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-4A = -24
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A = 6
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J = 3*A = 3*6 = 18
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Check how old they were 4 years ago.
A = 6-4 = 2
J = 18-4 = 14
14 = 7*2 ?
Correct.
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Answer: Amy is 6, and Jim is 18.
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Done.