\[\boxed{\text{498\ (498).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ \left\{ \begin{matrix} x \geq 2 \\ y \geq 1 \\ \end{matrix} \right.\ \ \]
\[\textbf{б)}\ \left\{ \begin{matrix} x < - 1 \\ y > 0\ \ \ \\ \end{matrix} \right.\ \]
\[\textbf{в)}\ \left\{ \begin{matrix} x + 2 \geq 0 \\ y - 3 \leq 0 \\ \end{matrix} \right.\ \]