The sum of n terms of two arithmetic progressions aree in the ratio `(5n+4):(9n+6)`.Find the ratio of their 18th terms.

The ratio of sum of the first n terms of two series in A.P is (3n + 8) : (7n + 15) . Prove that the ratio of their 12th terms is 7 : 16.

Find the term: 20+18+16+…. To the 16th term.

The n th term of a progression is 3n-5 .Find its 15th term.

The sum of the 4th and 8th terms of an AP is 24 and the sum of the 6th and 10th terms is 44.Find the first three terms of the AP.

The sum of fIrst n terms of an A.P series is 26n-2n^2 . Find the fifth term.

If the sum of the first n terms of an AP is 4n-n^2 ,what is the first term(that is S_1 )?What is the sum of first two terms?What is the second term?Similarly,find the 3rd,the 10th and nth terms.

In an A.P. the ratio of 7th term to 11th term is 19 : 31 and the sum of these two terms is 20.Find the sum of first twenty terms.

The sum of 4th and 8th term of an A.P. is 24 and the sum of 6th and 10th term is 44. Find the A.P.

Find the sum of first n terms of even natural numbers .

The sum of first n terms of an A.P. is m and that of first m terms is n. Prove that the sum of first m + n terms is -(m + n) .