\[a_{17} = 84;\ \ \ \ \ \ d = 6,5:\]
\[a_{17} = a_{1} + 16d\]
\[a_{1} + 16d = 84\]
\[a_{1} = 84 - 16 \cdot 6,5 = - 20.\]
\[S_{17} = \frac{a_{1} + a_{17}}{2} \cdot 17 =\]
\[= \frac{- 20 + 84}{2} \cdot 17 =\]
\[= 32 \cdot 17 = 544.\]
\[Ответ:544.\]