Adding And Subtracting Fractions Worksheet With Answer Key - Unit 3: Linear Equations Page 6
ADVERTISEMENT
1
2
3
4
5
6
7
8
92
How to
• • • • • • • • • • • • • • • • • Subtract Fractions
Facts to Know
(cont.)
Subtracting Fractions with Different Denominators
When subtracting fractions with different denominators, find a common denominator.
Sample: Lupe walks 1 –
mile to the train. She stops for coffee at Tom’s restaurant, which is 3 –
mile to
2
8
the train. How much further does she have to walk after Tom’s?
You’ll have to subtract 3 –
from 1 –
, but they don’t have common denominators.
8
2
Step 1
Find the least common denominator. The numbers 2 and 8
1 –
= 4 –
2
8
both evenly divisible by 8.
– 3 –
= 3 –
Raise 1 –
Step 2
to eighths.
8
8
2
1 –
Step 3
Subtract the fractions using the least common denominator.
mile
8
Subtracting Fractions from a Whole Number
When subtracting fractions from the whole number 1, you must change the number 1 to a fraction with
the same numerator and denominator as the denominator in the fraction.
Sample: Ian took one cup of sugar from a bag. He only used 3 –
cup to make ice tea.
4
How much sugar is left?
1 = 4 –
Step 1
Change 1 to a fraction, using the same number for the
4
numerator and denominator as the denominator of the
– 3 –
= 3 –
original fraction (1 cup = 4 –
4
4
cup).
4
1 –
cup left
Step 2
Subtract the fractions.
4
When subtracting a fraction from a whole number larger than 1, you must regroup.
Sample: 3 – 3 –
= ?
8
3 = 2 8 –
Regroup by changing 3 to 2 8 –
Step 1
.
8
8
(Remeber, 1 = 8 –
– 3 –
3 –
.)
=
–
8
8
8
Step 2
Subtract.
2 5 –
8
Subtracting Mixed Numbers
You can subtract mixed numbers provided the fractions have the same denominators.
Sample : 4 1 –
– 1 3 –
= ?
3
4
4 1 –
= 4 4 —
3 4 —
+ 12 —
3 16 —
=
Step 1
Find the lowest common denominator.
=
3
12
12
12
12
– 1 3 –
= 1 9 —
– 1 9 —
– 1 9 —
Since you can’t subtract 9 —
from 4 —
=
Step 2
;
=
4
12
12
12
12
12
regroup 1 as 12 —
from the 4. Add it to 4 —
.
12
12
2 7 —
12
Step 3
Subtract the fractions. Then subtract the whole numbers.
10
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education