SubArea: Arithmetic sequencesLevel: BProject ID: 2010000501Source Problem: 1003085206Accepted: 0Clonable: 1Easy: 0Find the sum of the first $15$ negative terms of the arithmetic sequence: $\left(7-2n\right)_{n=1}^{\infty}$.\( -225\)\( -135\)\( -240\)\( -180\)\( -450\)
