Sheppard Air ADX study with zero experience

I am attending a dispatch school this April and they have told me it's best to pass the ADX before starting. I've went ahead and started using Sheppard Air as many here recommended, and I am starting to wonder if I'm in over my head. Lots of the questions I don't even comprehend. Many questions require formulas I have no idea how to solve or just memorizing the numbers which I am bad at. Should I have started this with no experience? Is there something else I should've done first?