1. 2-4 Solving Addition &
Subtraction Equations
Math Notes
Algebra and Functions 1.2

2. Skills Needed...

3. Skills Needed...
Tell what you would do to get
the variable alone.

4. Skills Needed...
Tell what you would do to get
the variable alone.
x - 20

5. Skills Needed...
Tell what you would do to get
the variable alone.
x - 20
Add 20

6. Properties of Equality

7. Properties of Equality
You can add the same number to
both sides of an equation.

8. Properties of Equality
You can add the same number to
both sides of an equation.
You can subtract the same
number from both sides of an
equation.

9. Example 1
4 + 1= 5

10. Example 1
4+1 =5

11. Example 1
4 + 1 + 3= 5 + 3

12. Example 1
4 + 1 + 3= 5 + 3
8 = 8

13. Example 2
7 + 5 = 12

14. Example 2
7+5 = 12

15. Example 2
7 + 5 - 3 = 12 - 3

16. Example 2
7 + 5 - 3 = 12 - 3
9 = 9

17. Example 3
Solve x + 6 = 17

18. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
to get the variable alone?

19. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
Subtract 6
to get the variable alone?

20. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
Subtract 6
to get the variable alone?
STEP TWO: Use the Property
of Equality and subtract 6
on both sides.

21. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
Subtract 6
to get the variable alone?
STEP TWO: Use the Property
of Equality and subtract 6 X + 6 - 6 = 17 - 6
on both sides.

22. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
Subtract 6
to get the variable alone?
STEP TWO: Use the Property
of Equality and subtract 6 X + 6 - 6 = 17 - 6
on both sides.
STEP THREE: + 6 - 6 cancel out.
What is 17 - 6?

23. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
Subtract 6
to get the variable alone?
STEP TWO: Use the Property
of Equality and subtract 6 X + 6 - 6 = 17 - 6
on both sides.
STEP THREE: + 6 - 6 cancel out.
What is 17 - 6?

24. Example 3
Solve x + 6 = 17
STEP ONE: What can you do
Subtract 6
to get the variable alone?
STEP TWO: Use the Property
of Equality and subtract 6 X + 6 - 6 = 17 - 6
on both sides.
STEP THREE: + 6 - 6 cancel out. X = 11
What is 17 - 6?

25. Example 4
Solve n - 189 = 200

26. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
to get the variable alone?

27. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
Add 189
to get the variable alone?

28. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
Add 189
to get the variable alone?
STEP TWO: Use the Property
of Equality and add 189
on both sides.

29. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
Add 189
to get the variable alone?
STEP TWO: Use the Property
of Equality and add 189
on both sides.
n - 189 + 189 = 200 + 189

30. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
Add 189
to get the variable alone?
STEP TWO: Use the Property
of Equality and add 189
on both sides.
n - 189 + 189 = 200 + 189
STEP THREE: + 189 - 189 cancel out.
What is 200 + 189?

31. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
Add 189
to get the variable alone?
STEP TWO: Use the Property
of Equality and add 189
on both sides.
n - 189 + 189 = 200 + 189
STEP THREE: + 189 - 189 cancel out.
What is 200 + 189?

32. Example 4
Solve n - 189 = 200
STEP ONE: What can you do
Add 189
to get the variable alone?
STEP TWO: Use the Property
of Equality and add 189
on both sides.
n - 189 + 189 = 200 + 189
STEP THREE: + 189 - 189 cancel out. n = 389
What is 200 + 189?