[tex]\it (3n+4)\ \vdots\ (2n+1) \Rightarrow 2n+1\Big |\ 3n+4/_{\cdot2} \Rightarrow 2n+1\Big |6n+8\ \ \ \ (1)\\ \\ 2n+1\Big |2n+1/_{\cdot3} \Rightarrow 2n+1\Big |6n+3\ \ \ \ \ \ \ (2)\\ \\ (1),\ (2) \Rightarrow 2n+1\Big |6n+8-6n-3 \Rightarrow 2n+1|5 \stackrel{n\in\mathbb{N}}{\Longrightarrow}\ 2n+1\in\{1,\ 5\}|_{-1} \Rightarrow\\ \\ \Rightarrow\ 2n\in\{0,\ 4\}|_{:2}\Rightarrow x\in\{0,\ 2\}[/tex]
