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Subtract 1/21 from 18/20

18/20 - 1/21 is 179/210.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 20 and 21 is 420

    Next, find the equivalent fraction of both fractional numbers with denominator 420
  2. For the 1st fraction, since 20 × 21 = 420,
    18/20 = 18 × 21/20 × 21 = 378/420
  3. Likewise, for the 2nd fraction, since 21 × 20 = 420,
    1/21 = 1 × 20/21 × 20 = 20/420
  4. Subtract the two like fractions:
    378/420 - 20/420 = 378 - 20/420 = 358/420
  5. After reducing the fraction, the answer is 179/210

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