Find the sum of first 22 terms of an AP in which and 22nd term is 149.

We have; n = 22, d = 7 and a₂₂ = 149

We know;

a_n = a + (n – 1)d

Or, a = 149 – 147 = 2

The sum can be calculated as follows:

                 = 11*151

                 = 1661