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a b a − b
− = .
c c c

Fractions with the same denominator are called like fractions.
Example 101. Here are three examples involving addition or subtraction of like fractions:

1 2 1+ 2 3
+ = =
5 5 5 5
13 2 13 − 2 11 4
− = = =1
7 7 7 7 7
7 5 7 − 5 2 1
− = = = .
8 8 8 8 4
Notice that we reduced to lowest terms where necessary, and changed improper fractions to mixed
numbers.

3.8.1 Exercises

Add or subtract the like fractions as indicated. Reduce the final answers to lowest terms if necessary.
Change improper fractions to mixed numbers.

1 3
1. + =
5 5
7 13
2. + =
5 5
11 13 8
3. + + =
15 15 15
20 3
4. − =
51 51
5 4
5. − =
13 13

11 9 3
6. + − =
25 25 25
109 11
7. − =
7 7
13 1
8. − =
2 2
10 6 11
9. + − =
7 7 7
11 2 8
10. − + =
25 25 25

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