How do I Find the sum of the given arithmetic series

Question

anonymous · Answer

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anonymous · Answer

Me again.  You can use your same formula from before.  Think about what n has to be.  Do you know how to find the first and last term.

tkhunny · Answer

[25(10) + 14]+[25(11) + 14]+[25(12) + 14]+...+[25(400) + 14] = 

25(10 + 11 + 12 + ... + 400) + 391*14

Now what?

anonymous · Answer

Yes I do know how to find that but what is that i and how do I incorporate it?

anonymous · Answer

i refers to the numbers of the terms.  You are adding all terms from term 10 to term 400.  Next to the sigma is what you need to do with i to get what term 10 equals and what term 400 equals.

anonymous · Answer

Oh I thought the i represented some type of mathematical variable in math. Thanks again!