1. &
dding
ubtracting
ractions

2. Fractions Like denominators- just add the numerator.
Example: 2/5 + 2/5= 4/5

3. Like Denominators Guided Practice: 12/ 15 + 2/15
12/ /15
Try on your own: 6/23 + 7/23

4. Unlike denominators
Step 1: find the LCM of the denominators Step 2: multiply both the top and the bottom by that number
Step 3: Make sure it doesn’t need to be simplified
Look at the next slide for example

5. +
We need a common
denominator to add
these fractions.

6. 7 6 13 = = + 7 + 6 = 13 x 7 X 7 x 2 x 2 Make equivalent fractions.
Add the numerators = +
7 + 6 = 13
x 2 13

7. +
We need a common
denominator to add
these fractions.

8. 15 7 22 = + = 15 + 7 = 22 x 5 X 5 x 7 x 7 Make equivalent fractions.
Add the numerators =
x 7
= 22 22

9. We need a common
denominator to add
these fractions. +
Count by 7's
7, 14, 21, 28, 35, 42, 49, 56, 63
Count by 8's
8, 16, 24, 32, 40, 48, 56, 64, 72

10. 32 21 53 32 + 21 = 53 = + = x 8 x 8 x 7 x 7 Make equivalent fractions.
Add the numerators
x 7 +
= 53 =
x 7 53

11. +
We need a common
denominator to add
these fractions.
Count by 3's
3, 6, 9, 12, 15, 18, 21, 24, 27
Count by 5's
5, 10, 15, 20, 25, 30, 35, 40, 45

12. x 3 9
Add the numerators =
X 3
= 19
x 5 10 + =
x 5 19

13. +
We need a common
denominator to add
these fractions.
Count by 3's
3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33
Count by 11's
11, 22, 33, 44, 55, 66, 77…

14. 15 22 37 = + = 15 + 22 = 37 x 3 X 3 x 11 x 11 Make equivalent
fractions. =
X 3
x 11
Add the numerators 22 + =
= 37
x 11 37

15. +
We need a common
denominator to add
these fractions.

16. 18 11 29 = + = 18 + 11 = 29 x 6 X 6 x 11 x 11 Make equivalent
fractions. =
X 6
x 11 11 +
Add the numerators. =
= 29
x 11 29

17. We need a common
denominator to add
these fractions. +

18. +
We need a common
denominator to add
these fractions.

19. x 9 36
Make equivalent
fractions.
Make equivalent
fractions. = x9
x 5 35
Add the numerators.
Add the numerators. + =
= 71
= 71
x 5 71

20. Try These A D E B F C

21. Try These 10 9 17 27 A D 41 28 13 12 B E 19 20 26 21 C F

22. Subtracting Fractions
The steps are just like adding fractions, but instead of adding the numerators, you subtract the numerators.

23. -
We need a common
denominator to
subtract a fraction
from another.

24. 15 11 4 15 - 11 = 4 = = - x 5 x 5 x 11 x 11 Make equivalent fractions.
Subtract. =
= 4 -
x 11 4

25. 5 3 2 5 – 3 = 2 = - = x 5 x 5 x 1 x 1 Make equivalent fractions.
Subtract. - =
5 – 3 = 2
x 1 2