The sum of first 6 terms of an arithmetic progression is 42. The ratio of its 10th term to its 30th term is `1:3`. Calculate the first and 13th term of an AP.

Explanation

To solve the problem step by step, we will use the properties of arithmetic progressions (AP).

### Step 1: Understanding the problem
We know:
- The sum of the first 6 terms of an AP is 42.
- The ratio of the 10th term to the 30th term is 1:3.

Let the first term be \( a \) and the common difference be \( d \).
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