Question 1170564
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The statement of the problem is flawed, because no information is given about the actual ages, or the sum of the ages.  That makes it impossible to find a solution.<br>
If the sum of the ages had been given, the problem would still be flawed, because of the use of the phrase "his father is 5 times older than Dave".<br>
Nearly always, a casual reader interprets "5 times older than" to be the same as "5 times as old as".  But they are different.<br>
If an age is x, then the age that is 5 times AS OLD AS x is clearly 5 times x, or 5x.<br>
But if an age is x, then the age that is 5 times OLDER THAN x is x, plus 5 times MORE x, which is x+5x = 6x.<br>
The phrase that says one age is n times OLDER than another age should never be used in the statement of a math problem, because the meaning is probably not what the author of the problem intended.<br>