PA.2.1. Numbers, Number Systems and Number Relationships
2.1.4.F. Understand the concepts of addition and subtraction and their inverse relationships; understand the concepts of multiplication and division; use the four basic operations to solve problems, including word problems and equations.
PA.2.8. Algebra and Functions
2.8.4.A. Use the concept of equality and concrete objects to demonstrate understanding of commutative, associative, and identity properties.