Question 1142863
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The sum of Leo's age and Mario's age is 21, and Leo is 5 years younger than Mario.  That makes Mario 13 and Leo 8.  Use formal algebra if you want to determine that -- or simply find two numbers whose sum is 21 and whose difference is 5.<br>
The rest of the problem can't be answered, because the phrase "...3 times younger than..." has no useful meaning.<br>
We have found that Mario's age is 13.  If 13 is "3 times younger than their dad's" age, that means if their dad's age is x, then 13 is equal to x - 3x = -2x.  So that would mean -2x = 13, making their dad's age -6.5 -- which of course is nonsense.