Hi! This is my first time on this forum, but I need some excel help for creating a gradebook!

Basically, I have a list of quiz grades, some of which are 20 point quizzes, and some of which are 10 point quizzes. I need to drop the 3 lowest quiz scores, which I can do with this:
SUM A2:A18 - SMALL A2:A18,1 - SMALL A2:A18,2 etc.

But, I need to drop the corresponding total amount of points! So if I drop a 10 point quiz, i want to drop 10 points from the total, and if I drop a 20 point quiz, I need to drop 20 points from the total. Is there some kind of function that lets me drop 1 value and drop the corresponding same-row value in a different column? Hopefully my situation is clear, if not I will clarify until I find the answer!

Thank you in advance for your time and help!!