1. Chapter 3-3 Solve Equations by Adding/Subtracting
Unit 1
Chapter 3-3 Solve Equations by Adding/Subtracting

2. Solve equations by subtracting
You can used inverse operations to solve equations. Inverse Operations “undo” each other.
You can use the Subtraction Property of Equality to solve equations involving addition
Example 1: X + 3 = (Move the 3 because it is on the same side of the equal sign as the variable)
X = 4
Example 2: 16 + X = 12
(move the 16 because it is on the same side of the equal sign as the variable)
X = - 4

3. Solve equations by adding
You can solve some equations by adding the same number to each side. This property is called the Addition Property of Equality.
Ex 1) Y – 7 = 21 (move the 7 since it’s on the same side of the equal sign as the variable)
Y = 28
Ex 2) X – 10 = -10
X = 0

4. Let’s try some examples
Ex 1) X + 7 = - 8
Ex 2) X – 8 = 15
Ex 3) X + 2 =10
Ex 4) A – 3 = 13
Ex 5) 23 + Y =14
Ex 6)* C – (-3) = 9

5. Let’s check our answers
Ex 1) X + 7 = - 8
X = -15
Ex 2) X – 8 = 15
X = 23
Ex 3) X + 2 = 10
X =8
Ex 4) A – 3 = 13
A = 16
Ex 5) 23 + Y =14
Y = - 9
Ex 6)* C – (-3) = 9
C = 6