Find the 20th term from the last term of the A.P. 3, 8, 13, …, 253.

Here, common difference = d = 8 - 3 = 5 and last term = l = 253.

We know that the nth term from last is given by the formula:
nth term from end = l - (n - 1)d

∴ 20th term from end = 253 - (20 - 1)5 = 253 - 19 × 5 = 253 - 95 = 158.

Hence, the 20th term from last term of the A.P. 3, 8, 13, …., 253 is 158.