Suppose that $\sum_{k=1}^{n} a_{k}=0$ and $\sum_{k=1}^{n} b_{k}=1 .$ Find the values of
$$
\begin{array}{ll}{\text { a. } \sum_{k=1}^{n} 8 a_{k}} & {\text { b. } \sum_{k=1}^{n} 250 b_{k}} \\ {\text { c. } \sum_{k=1}^{n}\left(a_{k}+1\right)} & {\text { d. } \sum_{k=1}^{n}\left(b_{k}-1\right)}\end{array}
$$