wow, this is so clean code!
I'm from Indonesian

Thanks for the solution. I get to know about the reduce() function for the first time from your code.

I also thought of using a switch, but as you can see by the comments here, using switch(true) and then doing evaluations in each case is kind of an anti-pattern that can be hard to read and debug.
I would avoid and look for one of the other conditional options in this board.

Your points are not included in the array of your class's points. Do not forget them when calculating the average score!

You didn't take into account the length of your points

why?

lol, wont to start braind xD

My brain exploded when I saw how easy your solution looked lol

You should not put return 0, as it can be confused with examples like (18-18) or (18*0) or maybe when puyying (18/0) it is not logical that i'll get 0!.

no @imaNami brother, there was a note said "Your points are not included in the array of your class's points. Do not forget them when calculating the average score!

". so you have to add it separately.

там все добавлено

Just simple if else statements does the trick