This document provides instructions and examples for adding and subtracting mixed numbers: 1) Rewrite fractions with different denominators using the least common denominator. 2) Add or subtract the fractions, then the whole numbers. 3) Simplify if possible. Step-by-step examples are shown of adding and subtracting mixed numbers, including having students practice examples.

1. 6.4 Adding and
Subtracting Mixed
Numbers

2. Adding Mixed Numbers
Find the sum.
1
+
3
4
4
9
1
9
5
9
1. Rewrite the fraction using
LCD if denominators are
different.
2. Add or subtract the
fractions,
then the whole numbers.
3. Simplify if possible.
In this problem, the denominators are the
same, so begin with step 2.

3. Let’s Do More Examples!
Find the sum.
1
+
3
4
4
4
9
1
3
7
9
X3
=
X3
3
9
+
5
7
8
X2
1
4
=
X2
8
9
9
10
2
8
1
8
=
1
1
8
Add the whole numbers.

4. Subtracting Mixed
Numbers
Find the Difference.
1 17
20
3 X 4 12
=
- 1
5 X 4 20
5
= 1
20
4
3
X6
= 18
3
4 X 6 24
1
X4
- 1 6
2
14
24
=
X4
=
7
2
12
4
24
7
12
10 7
8
1
4
8
6
6
= 3
4
8
6
3
4

5. Now You Try!
Find the sum or difference.
3 X2 6
5
10
3
=
4
=
12
5 X 2 10
6
9
1
+ 7 10
- 1 12
10
15
10
= 1
5
10
11
=
1
2
9 =
12
3
1
2
3
3
4
3
4

6. Now You Try!
Find the sum or difference.
3 X2 6
5
10
3
=
4
=
12
5 X 2 10
6
9
1
+ 7 10
- 1 12
10
15
10
= 1
5
10
11
=
1
2
9 =
12
3
1
2
3
3
4
3
4