# & dding ubtracting ractions.

## Presentation on theme: "& dding ubtracting ractions."— Presentation transcript:

& dding ubtracting ractions

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

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

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

+ We need a common denominator to add these fractions.

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

+ We need a common denominator to add these fractions.

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

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

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

+ 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

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

+ 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…

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

+ We need a common denominator to add these fractions.

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

We need a common denominator to add these fractions. +

+ We need a common denominator to add these fractions.

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

Try These A D E B F C

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

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

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

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

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