[tex]\displaystyle\bf\\\left \{ {{14x-21\geq 7(1-x)-28} \atop {\dfrac{5x+2}{4} }+2\leq \dfrac{3x-3}{2} } \right. \\\\\\\left \{ {{14x-21\geq 7-7x-28} \atop {\dfrac{5x+2}{4} \cdot 4}+2\cdot 4\leq \dfrac{3x-3}{2} \cdot 4} \right. \\\\\\\left \{ {{14x+7x\geq 7-28+21} \atop {5x+2+8\leq (3x-3)\cdot 2}} \right. \\\\\\\left \{ {{21x\geq 0} \atop {5x+10\leq 6x-6}} \right. \\\\\\\left \{ {{x\geq 0} \atop {5x-6x\leq -6-10}} \right. \\\\\\\left \{ {{x\geq 0} \atop {-x\leq -16}} \right.[/tex]

[tex]\displaystyle\bf\\\left \{ {{x\geq 0} \atop {x\geq 16}} \right. \ \ \ \Rightarrow \ \ \ x\geq 16\\\\\\Otvet \ : \ x\in\Big[16 \ ; \ +\infty\Big)[/tex]