List of top Mathematics Questions on Sum of First n Terms of an AP asked in UP Board X

If sum of first 9 terms of an $A.P.$ is $81$ and the sum of first $17$ terms is $289$, find its first term and the common difference.
If the sum of first 7 terms of an A.P. is 49 and the sum of first 17 terms is 289, find the sum of first $n$ terms.