1/3 is less then or equal to 3x-1 is less then or equal to 3/4

What is your question.

Huh? Am I in grade school again? Next question, please.

No, this one is fine. Can you answer Tiffany Star's question or not?

First let's write out your problem in mathematical terms:
1/3 <= 3x-1 <= 3/4

Then we add 1 to all terms:
1 1/3 <= 3x <= 1 3/4

Then we divide all terms by 3:
4/9 <= x <= 7/12

Hope this is what you are looking for! :)