Question

Find the 20th term from the last term of the AP:3,8,13,..., 253.
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Answer 1

158

Explanation:

The sequence is 3, 8, 13, ..., 253.

Going backwards, it's 253, 248, 243, ..., 3.

First term is 253, common difference is -5.

The nth term is:

a = 253 − 5(n − 1)

The 20th term is:

a = 253 − 5(20 − 1)

a = 158