the sum of the first n terms of an AP whose first term is 8 and difference is 20 is equal to sum of 2n terms of another AP whose first term is -30 and common difference is 9. Find the AP

Given, sum of the first n terms of an AP whose first term is 8 and difference is 20 is equal to the sum of 2n terms of another AP whose first term is -30 and common difference is 9.

 So, according to the given condition,

Here, the value of n is coming in decimal which can't be possible. So, please recheck your query.

Moreover, your series for the first a.p will be:

8,  8 + 20,  8 + 20 + 20, ........

= 8, 28, 48, .......