SUBTRACTION: Example 3

Rule 19:
To subtract, the denominators must be equal. You essentially following the same steps as in addition.
1.
Build each fraction so that both denominators are equal.
2.
Combine the numerators according to the operation of subtraction or additions.
3.
The denominators will be the denominator of the built-up fractions.
4.
Reduce the answer.

Example:
Calculate tex2html_wrap_inline48 .
Answer:
The answer is tex2html_wrap_inline50 .
Solution:
Convert the 10 to the fraction tex2html_wrap_inline52 .
tex2html_wrap_inline48 can now be written tex2html_wrap_inline56 .

The denominators are different, so you must build each fraction to a form where they both have the same denominator. Since both 1 and 4 will divide evenly into 4, build the fractions to a denominator of 4.

tex2html_wrap_inline58 .

tex2html_wrap_inline56 can now be written tex2html_wrap_inline62.

Add the numerators: 40 - 3 = 37.
The answer is tex2html_wrap_inline66 .
This answer is already reduced, so you can skip step 4.

Check:
Now prove to yourself with your calculator that your answer is correct. Calculate 3 divided by 4 and subtract it from 10. Now divide 37 by 4. Both answers should be the same. If you are correct, the answers are the same (equivalent) and you have successfully combined a fraction and a whole number using subtraction.

If you would like to review another example, click on the word Example.

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Author:Nancy Marcus

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