Question 1120144
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Kim   + John < 16


(J+3) + J    < 16


2J + 3 < 16


2J < 16 - 3 = 13   ====>  J < 13/2 = 6.5.


Assuming John's age is an integer number, you get the solution set  J <= 6  for John.


<U>Answer</U>.  The solution set for John's age is  {1, 2, 3, 4, 5, 6}.
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P.S.  &nbsp;&nbsp;I do not consider the possibility for John to be &nbsp;0&nbsp; years old.


Although the child can be younger than 1 year, I never saw or heard the phrase "the child is 0 years old".


But since English is my second language, I do not consider myself as an expert in such kind of suggestions.