What is the sum of a 23–term arithmetic sequence where the first term is 9 and the last term is 119?

Question

amorfide · Answer

Sn=N(a1+an)/2

Sn= sum off
N= the Nth term in this case it is 23
A1=first term
an=last term
/2 means divide by 2

anonymous · Answer

THANK YOUU !

myininaya · Answer

@merchandize Please explain how you get your answers. Giving just the answers doesn't help anyone learn how to do the problem. Please try to teach the person how to come up with the answer on their own. This is OS's CoC (OpenStudy's Code of Conduct) : http://openstudy.com/code-of-conduct . Thanks and please.