\[- 64;32;\ - 16;\ldots\]
\[b_{1} = - 64;\ \ \ q = \frac{32}{- 64} = - \frac{1}{2} < 1.\]
\[S = \frac{b_{1}}{1 - q} = \frac{- 64}{1 + \frac{1}{2}} = - 64 \cdot \frac{2}{3} =\]
\[= - \frac{128}{3} = \ - 42\frac{2}{3}.\]
\[Ответ:\ - 42\frac{2}{3}.\]