Ms. Drake 7th grade Math Number Theory Lesson 20 Solving Equations by Adding or Subtracting

Number Theory Addition Property of Equality Algebraic Expression Base Coefficient Composite Number Constant Division Property of Equality Equation

Evaluate Exponent Greatest Common Factor (GFC) Inverse Operations Isolate the Variable Least Common Multiple (LCM) Like Terms Number Theory

Solve Standard Form Subtraction Property Of Equality Term Variable Verbal Expression

Number Theory Multiple Multiplication Property of Equality Numerical Expression Order of Operations Power Prime Factorization Prime Number Scientific Notation Solution

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 Variable Get the variable alone on one side of the equation.

x – 7 = 12 x – = 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.