The series 3, 8, 13, 18, ... is an arithmetic progression. In an AP the difference between two consecutive terms is constant. For the given series it is 18 - 13 = 13 - 8 = 8 - 3 = 5

The nth term of an AP is given by a + (n - 1)*d where the first term is a and the common difference is d.

We have a = 3 and the common difference d = 5

The 20th term is 3 + 19*5 = 3 + 95 = 98

**The required term of the given AP is 98.**