Assertion (A) : For an A.P., 3, 6, 9, ... , 198, $10^{th}$ term from the end is 168 .Reason (R) : If 'a' and 'l' are the first term and last term of an A.P. with common difference 'd', then $n^{th}$ term from the end of the given A.P. is l - (n - 1) d .