Add or subtract as indicated. Write the answer in simplest form. See Example 7.EXAMPLE 7 A...

Add or subtract as indicated. Write the answer in simplest form. See Example 7.

EXAMPLE 7 Add or subtract as indicated. Write each answer in simplest form.

a.

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b.

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c.

Solution

a. Fractions must have a common denominator before they can be added or subtracted. Since 20 is the smallest number that both 5 and 4 divide into evenly, 20 is the least common denominator (LCD). Write both fractions as equivalent fractions with denominators of 20. Since

then

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b. The LCD is 12. We write both fractions as equivalent fractions with denominators of 12.

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c. The LCD for denominators 2, 22, and 11 is 22. First, write each fraction as an equivalent fraction with a denominator of 22. Then add or subtract from left to right.