[MA2015] (6) 17 :
17 ) Use variables to represent numbers, and write expressions when solving a real-world or mathematical problem; understand that a variable can represent an unknown number or, depending on the purpose at hand, any number in a specified set. [6-EE6]
[MA2019] (6) 18 :
18. Determine whether a value is a solution to an equation or inequality by using substitution to conclude whether a given value makes the equation or inequality true. [MA2019] (6) 19 :
19. Write and solve an equation in the form of x+p=q or px=q for cases in which p, q, and x are all non-negative rational numbers to solve real-world and mathematical problems.
a. Interpret the solution of an equation in the context of the problem. [MA2019] (6) 21 :
21. Identify, represent, and analyze two quantities that change in relationship to one another in real-world or mathematical situations.
a. Use tables, graphs, and equations to represent the relationship between independent and dependent variables.