2. Solving Equations by Adding and Subtracting Think of an equation as a balance scale. When you solve an equation, your goal is to isolate the variable.

3. What you do to one side of an equation, you must do to the other side to keep it the equation balanced. Golden Rule of Equations ADDITION and SUBTRACTION “balance” each other MULTIPLICATION and DIVISION “balance” each other

4. Addition Property of Equality You can Add the same number to each side of an equation without changing the value. Y - 5 = 13 Y - 5 +(5) = 13 + 5 Y = 18

5. Subtraction Property of Equality You can SUBTRACT the same number from each side of an equation without changing the value. Y + 5 = 13 Y + 5 -(5) = 13 - 5 Y = 8

7. Examples 1.t – 58 = 71 2. x – 6 = -55 3. 114 + m = 249 4. x – 34 = -46

8. Examples Cont. 5. x + x = 64 6. x – x = 64 7. The sale price of a camera is $119. This is $35 less than the original price. What was the original price?

9. Division Property of Equality = 3x18

11. Examples 1. 5b = -235 2. -7h = 35 3. d/4 = 7

13. Remember: Whatever you do to one side of an equation, you must do to the other! Be careful: you cannot divide by zero: Division by ZERO is UNDEFINED