Reteaching
Name
12-9
Subtracting Mixed Numbers
The Plainville Zoo has had elephants for 12_46 years. The zoo has
had zebras for 5_36 years. How many years longer has the zoo had
elephants?
Step 1: Write equivalent fractions with the least
common denominator. You can use fraction strips.
&'
&
&
&
&
&
&
&
&
)
+
&
*
&
Step 2: Find the difference of 12_46 − 5_36. Subtract
the fractions. Then subtract the whole numbers.
Simplify the difference if possible.
&
&
&
(
+
&
&
&&&&
++++
3
4 − __
1
__
= __
6
6
6
12 − 5 = 7
4 − 5__
3 = 7__
1 years.
So, 12__
&
&
6
&&&
+++
6
6
Example 2: Sometimes you may have to
rename a fraction so you can subtract.
Find the difference of 6 − 2_38 .
6
rename
3
− 2__
8
5__
8
3
− 2__
8
8
__
35
8
For 1 through 4, find each difference. Simplify, if possible.
Remember: You may have to rename a fraction in order to subtract.
1.
5
4__
8
__
− 22
8
3
2__
8
2.
7
5___
12
___
−1 2
12
3.
5
4___
30
5
6__
3
− 1__
4
6
__
− 54
6
1
1__
1
1__
4
12
4.
6
5
5. Number Sense To find the difference of 7 − 3__
, how do you rename the 7?
12
12 = 1. I can rename 7 as 6___
12 .
I know that ___
12
12
1 miles this week. How many more
6. Robyn ran 5_34 miles last week. She ran 4__
4
miles did she run last week?
1 more miles
1__
2
3t
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