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### Course: 7th grade (Illustrative Mathematics)>Unit 5

Lesson 7: Lessons 1-6: Extra practice

# Associative and commutative properties of addition with negatives

The commutative and associative properties apply to addition, but not to subtraction. Rewriting subtraction as addition of the opposite is a superpower that suddenly lets us use the commutative and associative properties (without changing the value of the expression) in expressions that previously had subtraction involved. Created by Sal Khan.

## Want to join the conversation?

• I understand nothing of this.
• Hey liu Leon, it's fadethephaser2310. I'm going to be honest- it's pretty confusing. Adding negative numbers is like subtracting the number from your sum and subtracting a negative number is like adding to your sum. I hope this simplifies things.

• I don't understand why it's so easy.
(1 vote)
• I don't understand why this is useful.
(1 vote)
• why is it so hard?