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Subtract 21/18 from 20/21

1st number: 20/21, 2nd number: 1 3/18

20/21 - 21/18 is -3/14.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 21 and 18 is 126

    Next, find the equivalent fraction of both fractional numbers with denominator 126
  2. For the 1st fraction, since 21 × 6 = 126,
    20/21 = 20 × 6/21 × 6 = 120/126
  3. Likewise, for the 2nd fraction, since 18 × 7 = 126,
    21/18 = 21 × 7/18 × 7 = 147/126
  4. Subtract the two like fractions:
    120/126 - 147/126 = 120 - 147/126 = -27/126
  5. After reducing the fraction, the answer is -3/14

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