Question 989511
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M=Mo's age; D=Dan's age=3M
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D+6=2(M+6)
3M+6=2M+12
M=6 ANSWER 1: Mo is 6 years old.
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D=3M=3(6)=18 ANSWER 2: Dan is 18 years old. 
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CHECK:
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D+6=2(M+6)
18+6=2(6+6)
24=2(12)
24=24