Question 989154
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S=sister's age; F=Fred's age=3S
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F-4=5(S-4) Substitute for F.
3S-4=5S-20
16=2S
8=S ANSWER 1: Sister is 8 years old,
F=3S=3(8)=24 ANSWER 2: Fred is 24 years old.
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CHECK:
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F-4=5(S-4)
24-4=5(8-4)
20=5(4)
20=20