WEBVTT

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Here is the problem: 9 over 7 minus 8 over 3.

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Exact arithmetic with fractions (results kept in lowest terms).

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Rewrite both fractions with the least common denominator. The LCD of 7 and 3 is 21.

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Subtract the numerators and keep the denominator.

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Final answer in lowest terms.

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So the answer is negative 29 over 21.

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Fractions are combined over a common denominator for addition and subtraction, multiplied straight across, and divided by multiplying by the reciprocal. The result is reduced by the greatest common factor.

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Decimal check: negative 29 over 21 approximately negative 1.380952381.

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As a mixed number: negative 1 8 over 21.