Question 674243
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Solving the problem using all of the given information is a good exercise.  However, logical reasoning gives the answer with very little work.<br>
In age problems, all numbers are whole numbers.  So in this problem, the age Bob lived to must be a multiple of 6, 12, and 7.<br>
The least common multiple of 6, 12, and 7 is 84; so the age Bob lived to is an integer multiple of 84.  Since twice 84 is an unreasonable answer for the age at which Bob died, the answer has to be 84.<br>
ANSWER: 84<br>