CCSS.NCEX.Math.Content.6.EE.A - Apply and extend previous understandings of arithmetic to algebraic expressions.
- CCSS.NCEX.Math.Content.6.EE.A.1 - Write, read, and evaluate addition and subtraction expressions in which letters stand for numbers; i.e., 2 numbers with one number being represented by one letter (fixed variable 7+X=9 where x can only be one number).