1. The problem statement, all variables and given/known data An arithmetic series consists of 2n terms. Which are the two middle terms of the series? If the first term is a and the last term is b, find the middle terms and the sum of the series. 2. Relevant equations 3. The attempt at a solution I'm having problems finding out which terms are the middle terms. For a previous question all I did was find the average of the 1st and last term, but how would I know which term it is, I would know the value though. Please give me some guidance.