ADDITION AND SUBTRACTION OF FRACTIONS
Fractions must have the same denominators, or are
like fractions.
Adding and Subtracting Like Fractions
(1) Add or subtract the
numerators
(2) Do not add/subtract the denominator (it indicates the total portion)
3
|
+
|
4
|
=
|
7
|
;
|
5
|
-
|
2
|
=
|
3
|
9
|
9
|
9
|
7
|
7
|
7
|
Adding and subtracting Unlike Fractions
Method
Step1: Change ALL DENOMINATOTORS
to SAME VALUE (equivalent
fractions)
Step2: Add or subtract the NUMERATOR
Example
Solve 2
+ 1
5 3
Method
Step1: Convert DENOMINATOR
to SAME VALUE (equivalent
Fractions)
2
+ 1 = 2 x 3
+
1 x 5
5 3 5 x 3
3 x 5
Step2: Add or subtract the NUMERATOR
= 6
+ 5
15
15
=
11
15
Example
2
|
+
|
1
|
=
|
2 x3
|
+
|
1x5
|
;
|
5
|
-
|
2
|
=
|
5x3
|
-
|
2x2
|
5
|
3
|
5x3
|
3x5
|
6
|
9
|
6x3
|
9x2
|
|||||||
=
|
6
|
+
|
5
|
=
|
15
|
-
|
4
|
|||||||
15
|
15
|
18
|
18
|
|||||||||||
=
|
11
|
=
|
11
|
|||||||||||
15
|
18
|
Example
Solve 5
- 2
6 9
Method
Step1: Convert DENOMINATOR
to SAME VALUE (equivalent
Fractions)
5x3
– 2x2 = 15 - 4
6x3 9x2
18 18
Step2: Add or subtract the NUMERATOR
15-4 = 11
18 18
Examples (using diagrams)
The COMMOM DENOMINATOR is a MULTIPLE
of each of the denominators.
Adding And Subtracting Mixed Numbers
Example
Example
VIDEO
Example of Solving Fractions Word Problems using Model
