The fourth terms of an A.P. is 4. Then find the sum of the first 7 terms.

7^(th) term of an A.P. is 40. Then, the sum of first 13 terms is

If the first term of an A.P. is 2 and the sum of the first five terms is equal to one fourth of the sum of the next five terms, find (i) the 20th term (ii) the sum of first 30 terms.

If the sum of the first four terms of an AP is 40 and the sum of the first fourteen terms of an AP is 280. Find the sum of first n terms of the A.P.

The twelfth term of an A.P. is (-13) and the sum of its first four terms is 24, find the sum of first 12 terms of the A.P.

If the sum of first p terms of an A.P. is equal to the sum of the first q terms, then find the sum of the first (p+q) terms.

The sum of first 5 terms and first 15 terms of an A.P. are equal. Find the sum of its first 20 terms.

If the first term of an AP is 2 and the sum of the first five terms is equal to one-fourth of the sum of the next five terms, then what is the sum of the first ten terms?

If the first term of an A.P. is 3 and the sum of its first 25 terms is equal to the sum of its next 15 terms, then the common difference of this A.P. is: