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Define x :
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Let Cheryl be x years old.
Cheryl = x
Lisa = x + 6
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In two years time:
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Cheryl = x + 2
Lisa = x + 8
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Lisa will be twice as old as Cheryl :
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x + 8 = 2(x + 2)
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Solve x :
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x + 8 = 2(x + 2)
x + 8 = 2x + 4
x = 4
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Find their age :
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Cheryl = x = 4
Lisa = x + 6 = 4 + 6 = 10
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Answer: Lisa is 10 years old now.
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