Question 1015513
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J=John's age; M=Mark's age=J-3
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J+M=29
J+(J-3)=29
2J=32
J=16
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ANSWER: John is 16 years old.
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CHECK:
M=J-3=16-3=13
Mark is 13 years old.
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J+M=29
16+13=29
29=29
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