Помогите развязать |3x+1|≤ x+7

[latex]|3x+1| \leq x+7[/latex] [latex] \left \{ {{3x+1 \leq x+7} \atop {3x+1 \geq -x-7}} \right. [/latex] [latex] \left \{ {{3x-x \leq 7-1} \atop {3x+x \geq -1-7}} \right. [/latex] [latex] \left \{ {{2x\leq 6} \atop {4x \geq-8}} \right. [/latex] [latex]\left \{ {{x\leq 3} \atop {x \geq-2}} \right. [/latex] Ответ: [-2;3]