\[a_{n} = - 170 + \frac{4n}{5}\]
\[- 170 + \frac{4n}{5} < 0\]
\[\frac{4n}{5} < 170\]
\[4n < 850\]
\[n < 212,5 \Longrightarrow 212\ \]
\[отрицательных\ членов.\]
\[Ответ:212.\]