if youre struggling with studying, think of it like this
studying in your room is gonna be extremely hard, all the fucking distractions like ur PC, tv, phone, whatnot, pick a spot in the house in which you arent near your pc, you can still have your phone near you for easy internet access but keep it faced down, some people study better in complete silence some people like some background noise, youll have to find out which you are.
try to give yourself clear objectives, your brain works better like that. Say, "im going to do 3 problems and then take a break", or "im gonna read 20 pages and write down notes, then grab a drink" and get to work... many times I find people continue to do more problems after they finish because they get into a rythm, if not, its ok, take that break, but no longer than 5 minutes (assuming the problems dont take more than 15-30 minutes... youre 13 how hard can math be)
and thats it... give yourself tiny objectives, and youll succeed
YOURE NOT STUPID, YOURE JUST NOT USED TO THE THOUGHT PROCESS, I thought i was retarded in math, but when I did my work, i found it to be ENJOYABLE
maximize ur potential brah