College Algebra (10th Edition)

$15,960$
The sequence is arithmetic with common difference d=2, $a_{1}=14.$ The sum $S_{n}$ of the first $n$ terms of $\left\{a_{n}\right\}$: $S_{n}=\displaystyle \frac{n}{2}\left[2a_{1}+(n-1)d\right]$ $S_{120}=\displaystyle \frac{120}{2}\left[2(14)+2(120-1)\right]$ $=60(226)=15,960$