Multiple logic tests in if(

Hoping someone can help me out with this as I really have no idea where to start. I'm trying to make a score system so that:

Scores greater than 100 = 1 point
Scores between 80 and 99 = 2 points
Scores less than 80 = 3 points

Attached is what I have so far. I don't know how to nest if functions. I hope I explained it well enough. I'm thinking I might create a separate worksheet with a grid of possible outcomes, but I know there's an easier way than that.

Any help would be greatly appreciated!!