studies

what does he like? may be he has some dream and he thinks that he doesn't need study...or he doesn't have? then it's just lazy. There good ways for person to study - that he'she has some goal and study is necessary for it. Or just to enjoy good marks...(as for me I had both these stimulators) anyway if you want to solve this problem, first thing what you must do - to find reason, then find way

Let him to do their interested field, it will help to your brothe he may grow in that interested field.