Use a Variable to Write an Algebraic Expression

(6) Expressions, equations, and relationships. The student applies mathematical process standards to use multiple representations to describe algebraic relationships.

(Y7) Introduce the concept of variables as a way of representing numbers using letters (ACMNA175)

(Y7) Create algebraic expressions and evaluate them by substituting a given value for each variable (ACMNA176)

6.EE.2 Write, read, and evaluate expressions in which letters stand for numbers.