Chapter 8.3, Problem 60E

In Exercises 57-62, let

$\begin{array}{cc}& \begin{array}{c}\left\{a_n\right\}=-5,10,-20,40,\mathrm{...},\\ \left\{b_n\right\}=10,-5-20,-35,\mathrm{...},\end{array}\\ and& \\ & \left\{c_n\right\}=-2,1,-\frac{1}{2},\frac{1}{4},\mathrm{...},\end{array}$

Find the difference between the sum of the first 11 terms of {a_n} and the sum of the first 11 terms of {b_n}.