the sum 11 terms of an AP is 891, find the 25th term and 45th if the common differences is 15.... answer it for me please.

2 answers

I assume you mean that the sum of the first 11 terms is 891. You have d, so just find a:

11/2 (2a+10*15) = 891

Having a, now just find
a+24d and a+44d
I don't know please teach me