The sum of first 15 terms of an A.P. is 750 and its first term is 15. Find its 20th term.

If the sum of the first 14 terms of an AP is 1050 and its first term is 10, find the 20th term.

If the sum of the first 14 terms of an AP is 1050 and its first term is 10 , find the 20th term .

The sum of first 21 terms of an A.P. is 28 and the sum of the 1st 28 terms is 21. Show that one term of the progression is zero and find the sum of the preceding terms.

If the pth term of an A.P. is q and the qth term is p , then find its rth term.

The sum of first ten terms of an A.P. is 155 and the sum of first two terms of a G.P. is 9. The first term of the A.P. is equal to the common ratio of the G.P. and the first term of the G.P. is equal to the common difference of the A.P. Find the two progressions.

If fourth term of an HP is 3/5 and its 8th term is 1/3 , then find its first term.

The sum of first 6 terms of a G.P. is 9 times the sum of its first 3 terms. Find the common ratio of the G.P.

The sum of the first p terms of an A.P. is q and the sum of the first q terms of the same A.P. is p. Find the sum of the first (p+q) terms of the A.P.

If the sum of first n terms of G.P. is S and the sum of its first 2n terms is 5S, then show that the sum of its first 3n terms is 21S.

If the seventh term of an A.P. is 1/9 and its ninth term is 1/7 , find its 63rd term.