First, find the difference between each number in the sequence.... 34 - 25 = 9. 25 - 16 = 9 and 16 - 7 = 9... So, there is a constant difference of 9 between each number of the sequence. To find the 30th term, you could expand the sequence out to 30 (which is a good way to check your answer, but tedious)... So, simply add the 1st value of the sequence to the difference and multiply by 30 to find your 30th value.... 7 + 9 x 30 = 16 x 30 = 480.
Therefore, the 30th term is 480.