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To do this, first find the lowest common multiple, unless one is obvious.

Say 1/7 - 2/5 - 1/4 = ? Now the lowest common multiple of the denominators, (the bits at the bottom), is 7 x 5 x 4 = 140. check my math!!!

so we have 20/140 (for the 1/7), 28/140 (for the 2/5) and 35/140 (for the 1/4).

So for the curious example offered, we have (20 - 28 - 35) /140 which equals

-43/140. [check my math!!]

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Wiki User

14y ago
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Wiki User

13y ago

well you first check if there are mixed numbers (a number with a fraction at the end) if it is turn it into an improper fraction by multiplying the fractions denominator (bottom number) by the number then adding the asnwer to the numerator (top umber) then make sure they both have the same denominator by finding LCM, or if you don't know what that is just multiply them. remember that whatever you multiply the bottom number by you multiply the top number by! then when there all set you line the m up and subtract the top numbers only and put that over the same denomonator as the two other ones. if you can simplify you should :D that's my step by step guide, hope it helps!

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Wiki User

12y ago

you have to subtract Numerator NOT the denominator say 5\6 - 3\6= 5-3 =2 so the answer would be 2\6

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Anonymous

Lvl 1
4y ago

Work it out yourself

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Q: How to subtraction fractions?
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Related questions

How is subtracting fractions different from adding fractions?

In subtraction you take away rather than add. Also, addition is commutative, subtraction is not so the order of the numbers does matter for subtraction.


What Proper fractions that have the same denominator in addition or subtraction are called?

like fractions


Why do you have to find a common denominator?

Addition or subtraction of fractions require "like" fractions: that is, fractions with the same denominator.


What are the rules for fractions?

addition,subtraction,multiplication,division


Why change mixed numbers to improper fractions?

For addition, subtraction, division and multiplication with other fractions


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action attraction subtraction


What is the meaning of addition and subtraction of similar fraction?

Similar fractions are fractions with the same denominator. In order to add or subtract fractions they need to be similar.


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What is the purpose of finding an LCM?

It assists in the proper addition and subtraction of fractions.


How do you use greatest common factor with addition and subtraction of fractions?

You don't. You use the GCF to reduce the answer once the addition or subtraction is complete.


How are equivalent fractions used in renaming when subtracting?

When subtracting one fraction to another, one or both fractions are renamed so that they have the same denominators. Then the result of the subtraction is the equal to the subtraction of the numerators divided by the common denominator.


In order to perform this opertation fractions must have the same denominators?

Addition or subtraction