Lets say i had an 80% in a class, yet i got a 100% percent on the midterm, which is 10% of my grade. what would my new grade be?

You can do a quick calculation of the grades with their weighted percent!!

if you assume that your grade combines to 100% total, and the midterm that's 10% of your grade has yet to be factored in, this would mean that you've received 90% of your grades. in this 90%, you got an 80.

so, at 90% you scored an 80%. at 10% you scored a 100%. you need to combine the two of these to represent how your assignments/tests/homework combine to 100% (90 of that finished, 10 of that coming from your midterm). create an addition problem that represents this, converting percents to decimals:

(0.90)(0.80) + (0.10)(1.00) = .82, or 82%

your final grade would be an 82% in the class.