Notăm ce le trei numere cu a, b, c.
[tex]\it a+b+c=198\ \ \ \ \ \ (1)\\ \\ b=\ \dfrac{a}{4}+12|_{\cdot4} \Rightarrow 4b=a+48 \Rightarrow a=4b-48\ \ \ \ \ \ (2)\\ \\ c=\dfrac{b}{2}+15\ \ \ \ \ (3)\\ \\ \\ (1),\ (2),\ (3) \Rightarrow 4b-48+b+\dfrac{b}{2}+15=198 \Rightarrow 5b+\dfrac{b}{2}-33=198|_{+33} \Rightarrow \\ \\ \Rightarrow \dfrac{11b}{2}=231|_{+33}b=231\cdot\dfrac{2}{11} \Rightarrow b=21\cdot2=42[/tex]
