The general term of an arithmetic sequence is,

Where ,
= nth term.
= First term
and d = common difference.
The given sequence is: 57, 66, 75, 84, 93, ...
Here
= 57,
d = 66 - 57 = 9
We need to find the 250th term. So, n = 250.
Next step is to plug in these values in the above formula. Therefore,

= 57 + 249 * 9
= 57 + 2241
= 2298
Therefore, 250th of this sequence is 2298
Hope this helps you!