<PRE><B>Question 484025</B>
I would assume if you let x, x+1, x+2 be the numbers then


*[tex \LARGE 13 \le x + (x+1) + (x+2) \le 15]


*[tex \LARGE 13 \le 3x+3 \le 15]


in which the three numbers are uniquely determined because their sum must be a multiple of 3 (i.e. 15).</PRE>