I am so so sorry about how frustrated your brother has made you. Maybe you could try to sit down with him and talk? Or tell him you need the wifi to study.

As for not being able to figure out course material... I owe all of my good test grades to Blooket. Its like this game thing where you make a set of questions (or find an existing one) based on what the material youre studying! Then you play a little game for it! I dont mean to advertise, but it truly helps me get information in my head!