SOLUTION: 75+72+69+66+.....21+18+15

Question 1207639: 75+72+69+66+.....21+18+15
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20849) (Show Source): You can put this solution on YOUR website!

+.....+
pattern:
common difference is
1st term:
2nd term:
3rd term:
4th term:
5th term:
6th term:
7th term:
and so on

Answer by ikleyn(52781) (Show Source): You can put this solution on YOUR website!
.
75+72+69+66+.....21+18+15
~~~~~~~~~~~~~~~~

They want you find the sum of an arithmetic progression. First term is 75; last term is 15; common difference is 3. The sum is the product of the mean by the number of terms. The mean is = = 45. The number of gaps = = = 20. The number of terms is 20+1 = 21. The sum is mean * the number of terms = 21 * 45 = 945. ANSWER

Solved.

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