\[\boxed{\text{64\ (64).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\ 11 \leq x < 12\]
\[\textbf{б)}\ 50 < y \leq 100\]
\[\textbf{в)}\ 350 < a < 400\]
\[\textbf{г)} - 100 \leq b \leq - 10\]