Question

3) The sum of first 13 terms and the sum of next 12 terms of an arithmetic sequence are
equal. If its common difference is 3.
-
a) How many times of the common difference will be the difference between 1 and first
terms of this sequence ?
b) What is the 13 term of this sequence ?
c) What is the sum of first 25 terms of this sequence?​

Answer 1

Answer:

afterwards I will answer