## Algebra and Trigonometry 10th Edition

$26425$
The sum of the first $n$ terms of an arithmetic sequence can be obtained by the following formula: $\frac{n(a_1+a_n)}{2},$ where $a_1$ is the first term, $a_n$ is the nth term and $n$ is the number of terms. Thus the sum:$\frac{50(357+700)}{2}=25\cdot1057=26425$