Complete the subtraction sentence - up to 18

Learning Objectives Translate a 'subtraction sentence' into a formal linear equation with one variable. Solve for an unknown variable in first-degree equations of the form a - x = b and x - a = b. Apply the properties of equality (specifically the Addition and Subtraction Properties) to isolate a variable. Model real-world scenarios using subtraction-based linear equations where the values are 18 or less. Verify the solution to a linear equation by substituting the value back into the original expression. Represent subtraction equations on a number line to visualize the relationship between the terms. If your phone started with 18 GB of free space and now has 7 GB left, how much did you use? 🤔 You just solved an algebraic equation without even realizing it! This...

TermDefinitionExample VariableA symbol, typically a letter like x or y, used to represent an unknown numerical value in an expression or equation.In the equation 18 - x = 10, the variable 'x' represents the number that, when subtracted from 18, results in 10. EquationA mathematical statement asserting that two expressions are equal, indicated by an equals sign (=).15 - y = 9 is an equation because it states that the expression '15 - y' is equal to the value '9'. ExpressionA combination of numbers, variables, and operation symbols that represents a mathematical value. It does not contain an equals sign.The part '18 - x' from our previous example is an algebraic expression. Solution of an EquationThe specific value of a variable that makes an equation...

Addition Property of Equality If \(a = b\), then \(a + c = b + c\) Use this rule to solve for a variable when a number is being subtracted from it (e.g., in x - 5 = 10) or to eliminate a negative variable (e.g., in 18 - x = 7). Adding the same value to both sides maintains the equality. Subtraction Property of Equality If \(a = b\), then \(a - c = b - c\) Use this rule to solve for a variable when a number is being added to it. Subtracting the same value from both sides maintains the equality and helps isolate the variable. Solving for a Subtrahend (The number being subtracted) For an equation \(a - x = b\), the solution is \(x = a - b\) This is the result of applying properties of equality. To isolate x, you can add x to both sides (a = b + x) and then subtract b fr...