# Find the 20th term from the last term of the AP : 3, 8, 13, . . ., 253

**Solution:**

The formula for n^{th} term of an AP is a_{n} = a + (n - 1) d

Here, a_{n} is the n^{th} term, a is the first term, d is the common difference and n is the number of terms.

Given A.P. is 3, 8, 13, ..., 253

As the 20^{th} term is considered from last, so a = 253

Common difference, d = 3 - 8 = - 5 (Considered in reverse order)

We know that the nth term of an A.P. is a_{n} = a + (n - 1) d

So, 20^{th} Term is a_{20} = a + (20 - 1)d

a_{20} = 253 + (20 - 1)(- 5)

= 253 - 19 × 5

= 253 - 95

= 158

Answer: 20^{th} term from the last term is 158.

**Video Solution:**

## Find the 20th term from the last term of the AP : 3, 8, 13, . . ., 253

### Class 10 Maths NCERT Solutions Chapter 5 Exercise 5.2 Question 17 - Chapter 5 Exercise 5.2 Question 17

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

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