\[\boxed{\text{990\ (990).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[x - y = - 5;\ \ \ \ \ y = x + 5\]
\[при\ x = 5 \Longrightarrow \ y = 10\]
\[\text{\ \ \ \ \ \ \ \ }x = - 5 \Longrightarrow \ \ y = 0\]
\[при\ y = 5 \Longrightarrow \ \ x = 0\]
\[Ответ:в).\]