\[\boxed{\text{881\ (881).\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[y = kx + b;\ \ \ \ C\ (0;4);\ \ \ \ \]
\[D\ ( - 8;0)\]
\[0 \cdot k + b = 4 \Longrightarrow \ \ b = 4\]
\[- 8 \cdot k + b = 0\]
\[- 8k + 4 = 0\ \ \]
\[- 8k = - 4\ \]
\[k = 0,5\]
\[Ответ:b = 4;\ \ \ k = 0,5.\]