In an A.P., `S_n = 5,a=5/7 and d = -1/21`. Find n, Also, explain the double answer.

In an AP :- given a = 3, n = 8, S = 192, find d.

If the first term a_1 of an A.P. is 22, the common difference d = -4 and the sum to n terms is 64, find n. Explain the double answer.

In an AP :- given a = 5, d = 3, a_n = 50 find n and S_n .

In an AP :- given a_n = 4, d=2, S_n =-14, find n and a .

In an AP :- given a = 8, a_n = 62. S_n =210, find n and d .