This is for me chemistry class: For chemistry:

Labs are worth 25%
Unit test 40%
Quizzes 10%
Assignment 25%

I got an 91% on my assignment, a 83% on my other assignment. A 70% on my lab and a 50% on my test. What’s my grade ?

To calculate your grade, you can use the following formula:

(0.25 * lab + 0.4 * test + 0.1 * quiz + 0.25 * assignment) / total possible points * 100

Plugging in your grades:
(0.25 * 70 + 0.4 * 50 + 0.1 * 0 + 0.25 * ((91 + 83) / 2)) / 100 * 100
(17.5 + 20 + 0 + 25) / 100 * 100
62.5 / 100 * 100
62.5 %

Your grade is 62.5%.