Please help with Algebra two question

Please explain:
Find the 30th term of the following arithmetic sequence 4, 7, 10, 13, 16, .......

well it goes up in 3, so 3n
then it is 3n + 1 (e.g. 4, 7 ,10, 13...)
3 x 30 = 90
If 3n+1 then the 30th term is 91

hopes this helps

Assuming that the sequence adds 3 to the previous number and starts with 4 as the first number you could find any number in the sequence by doing (1+n*3) where n is the term.
1st = 1+1*3 = 4,
2nd = 1+2*3 = 7
3rd = 1+3*3 = 10
4th = 1+4*3 = 13
5th = 1+5*3 = 16 ...
30th = 1 +30*3 = 91

What would the 30th number of the sequence be?

Sorry, i don't knooo!!