# What is the sum of the arithmetic sequence 140, 135, 130 , if there are 35 terms?

Jul 13, 2015

If there are 35 terms, the last term will be 34 steps down from the first. The common difference is $- 5$.
The last term will be $140 - \left(34 \cdot 5\right) = - 30$
$S u m = \frac{140 + \left(- 30\right)}{2} \cdot 35 = 1925$