What is 20th term from the end of the AP 3, 8, 13, ..., 253?

Here, First term = a = 3

Common difference = d = 8 - 3 = 5

Last term = l = 253

To find: 20^th term from end.

So, n^th term from end is given by:

a_n = l - (n - 1)d

∴ 20^th term from end is:

a₂₀ = 253 - (20 - 1) × 5

= 253 - 95

= 158

∴ 20^th term from the end is 158.