# Math Help - Help with Sequences and Series Problem

1. ## Help with Sequences and Series Problem

The sum of the first twelve terms of an arithmetic sequence of real numbers is 60. The first term is -6. What is the sum of the first twenty terms?

2. ## Re: Help with Sequences and Series Problem

Originally Posted by Espionage
The sum of the first twelve terms of an arithmetic sequence of real numbers is 60. The first term is -6. What is the sum of the first twenty terms?
Suppose that $S_n$ is the sum of the first n terms and d is the common difference then $S_n=a+(n-1)d$ where $a$ is the first term.

3. ## Re: Help with Sequences and Series Problem

Thank you very much.