Given: 3, 8, 13, 18, ……

Here a = ; d = a₂ – a₁ = – =

Let ‘’ be the n^th term of the given A.P.

∴ a_n = a + (n – 1) d

⇒ = + (n – 1)

⇒ = + n –

⇒ n = +

∴ is the 16^th term of the given A.P.