6th Grade Math Textbook, Fundamentals

Add or subtract. Express your answer in lowest terms.

1. () 2. () 3.  4. 

5.Discuss and Write Explain how you would subtract from.

11

20

 2

10

4

5

7

10

 4

5

9

10

 4

15

3

5

 5

8

 5

16

Remember:The Subtraction Principle:

aba(b)

To subtract fractions with like or unlike signs,

apply the same rules you use for subtracting

integers. If the fractions have unlike denominators,

use the LCD to find a common denominator.

Subtract with Like Denominators,

Like Signs

Subtract: ()

• Subtract by adding the opposite of the
  number being subtracted.
  () ()

So ().

Subtract with Unlike Denominators,

Like Signs

Subtract: ()

• Subtract by adding the opposite of
  the number being subtracted.
  () 


• Find the LCD.
  Multiples of 12: 12, 24, 36...
  Multiples of 8: 8, 16, 24, 32...


• Use the LCD to rename any fractions.
  



• Express the answer in lowest terms.
   

So ().

The LCD

is 24.

 11

24

 1

8

 7

12

The negative addend has the greater

absolute value, so the answer is negative.

 11

24

3

24

 14

24

 14  3

24

1

8

 14

24

 7

12

3

24

1 • 3

8 • 3

7 • 2

12 • 2

1

8

 7

12

 7

12

 1

8

 1

8

 7

12

 2

11

 5

11

 2

11

3

11

 5  3

11

 5

11

 3

11

 5

11

 3

11

 5

11

The negative addend has the greater

absolute value, so the answer is negative.

 3

11

Subtract with Like Denominators,

Unlike Signs

Subtract: ()

• Subtract by adding the opposite of the
  number being subtracted.
  ()  

So ().

Subtract with Unlike Denominators,

Unlike Signs

Subtract: ()

• Subtract by adding the opposite of
  the number being subtracted.
  () 


• Find the LCD.
  Multiples of 16: 16, 32...
  Multiples of 4: 4, 8, 12, 16, 20...


• Use the LCD to rename any fractions.
  


• Express the answer in lowest terms.
    1

So ()1.

The LCD

is 16.

5

16

9

16

5

16

21

16

12

16

9

16

3 • 4

4 • 4

12

16

3

4

9

16

 3

4

9

16

9

16

 3

4

The addends are both positive,

so the answer is positive.

9  12

16

3

4

 3

4

3

5

1

5

3

5

2

5

1

5

1

5

 2

5

Both addends are positive,

so the answer is positive.

1  2

5

 2

5

 2

5

1

5

Lesson 5-6 for exercise sets. &KDSWHU 

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