To find the sum of the first \(70\) terms of the arithmetic sequence \(-11, -6, -1, 4, \cdots\), we need to find out what the last term equals.
The first terms is \(-11\) and the common difference is \(5\), so the \(70\)th term equals \(-11\) plus \(69\) times \(5\), or \(334\).
The sum of the arithmetic sequence equals the sum of the first and last terms times half the number of terms, so the sum equals \(( -11 + 334 )( 35 ) = 11,305\).