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Unit 7. Subtraction of Common Fractions. Subtracting fractions is almost like addition. You find the common denominator and make equivalent fractions. Subtract the numerators. When subtracting mixed numbers, there may be times when a larger fraction
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Unit 7 Subtraction of Common Fractions
Subtracting fractions is almost like addition. You find the common denominator and make equivalent fractions. Subtract the numerators. When subtracting mixed numbers, there may be times when a larger fraction is being subtracted from a smaller fraction.
You cannot subtract 9/15 from 5/15. Take 1 from the whole number 5, this leaves 4. Convert the 1 to an equivalent fraction with a denominator of 15. The numerator is also 15. Now add this fraction to the 5/15. Then 9/15 can be subtracted from this new fraction. This process is sometimes called borrowing.
Now subtract the whole numbers and also subtract the fractions.
Use the following guidelines when subtracting common fractions: • Find the lowest common denominator. • Make equivalent fractions with lowest common denominators. • You may have to borrow to complete the subtraction. • Reduce the answer to the lowest terms.
An equally valid way to subtract two mixed numbers is to convert the numbers totally to fractions, subtract, and then convert the answer to a mixed number.