If the sum of n terms of an A.P. is 210 and the sum of its first n-1 terms is 171, find its nth term.
Answer: A
The nth term of a series is the difference between the sum of the first n terms and the sum of the first n-1 terms. \(a_n = S_n - S_{n-1}\). Given \(S_n = 210\) and \(S_{n-1} = 171\). Therefore, \(a_n = 210 - 171 = 39\).