the sum of 11th terms of an a p is 891,find the 28th and 45th terms if the common difference is 15
You know that d = 15 and
a + 10d = 891
so a + 150 = 891
a = 741
now you know a and d, find
a + 28d , the 28th term
same for 45 term, find a + 44d