(B) Represent and solve multi-step problems involving the four operations with whole numbers using equations with a letter standing for the unknown quantity
(Y7) Introduce the concept of variables as a way of representing numbers using letters (ACMNA175)ACMNA177
(Y7) Extend and apply the laws and properties of arithmetic to algebraic terms and expressions (ACMNA177)
6.EE.2.A Write expressions that record operations with numbers and with letters standing for numbers. For example, express the calculation "Subtract y from 5" as 5 - y.6.EE.2.B
6.EE.2.B Identify parts of an expression using mathematical terms (sum, term, product, factor, quotient, coefficient); view one or more parts of an expression as a single entity. For example, describe the expression 2 (8 + 7) as a product of two factors; view (8 + 7) as both a single entity and a sum of two terms.