Ms. Drake 7th grade Math

Number Theory

Lesson 20Solving Equations by Adding or Subtracting

Number TheoryAddition Property of EqualityAlgebraic ExpressionBaseCoefficientComposite Number ConstantDivision Property of EqualityEquation

EvaluateExponentGreatest Common Factor (GFC)Inverse OperationsIsolate the VariableLeast Common Multiple (LCM)Like Terms

Number Theory

Number Theory

SolveStandard FormSubtraction Property Of EqualityTermVariableVerbal Expression

Number TheoryMultipleMultiplication Property of EqualityNumerical ExpressionOrder of OperationsPowerPrime FactorizationPrime NumberScientific NotationSolution

Solving an equation is like balancing a scale. If you add

the same weight to both sides of the scale it will remain

even.

Think of the equation x - 7 = 12

as a balance scale.The equal sign keeps

the balance, so whatever you do to

one side of the equation you must do to the other side

of the equation.

Isolate the VariableGet the variable alone on one side of the equation.

x – 7 = 12x – 7 + 7 = 12 + 7

x + 0 = 19 x = 19

y + 8 = 14

y + 8 – 8 = 14 – 8 y + 0 = 6 y = 6

To solve an addition problem use subtraction.

To solve a subtraction problem use addition.

Let’s do a few examples.

…Until next time try these problems.