Question 1167684
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    x*(x+8) = 153 = 9*17.



You can solve this quadratic equation or, alternatively,

you may guess the answer based on decomposition  153 = 9*17, where the factors  17  and  9  differ by  17-9 = 8 units.


<U>ANSWER</U>.  Juan is 9 years old.
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Solved.