Adding/ Subtracting Fractions

Steps

100

What is the 1st step when solving fraction addition and subtraction problems?

Check for a common denominator

200

What is the 2nd step when adding/subtracting fractions with unlike denominators?

Find a common denominator.

300

What is the 3rd step when adding and subtracting fractions with unlike denominators?

After changing the denominators we must change the numerators.

(if we multiply the bottom we must multiply the top)

400

What is the 4th step when adding and subtracting fractions with unlike denominators?

Add or subtract the numerators. The denominators stay the same. 

500

When subtracting mixed numbers and I am unable to subtract my numerators, which number am I going to borrow from?

The whole number.

Like Denominators

100

1/2 + 1/2 =

2/2

200

1/4 + 2/4 =

3/4

300

1/5 + 3/5 =

4/5

400

6/12 - 4/12 =

2/12

500

13/25 - 10/25 =

3/25

Addition With Unlike Denominators

100

3/5 + 1/7 =

26/35

200

2/4 + 3/9 =

30/36

300

5/10 + 1/3 =

25/30

400

1/8 + 3/5 =

29/40

500

2   8/10  +  5   1/20 =

7   17/20

or

7   170/200

Subtraction with unlike denominators

100

3/5 - 4/10 =

2/10

or

10/50

200

3/4 - 1/5 =

11/20

300

6/7 - 3/5 =

9/35

400

3  1/4  -   1   1/2=

1   3/4

500

5   1/3  -  2   1/2 =

2   5/6