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Subtract 7/20 from 1/21

1/21 - 7/20 is -127/420.

Steps for subtracting fractions

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

    Next, find the equivalent fraction of both fractional numbers with denominator 420
  2. For the 1st fraction, since 21 × 20 = 420,
    1/21 = 1 × 20/21 × 20 = 20/420
  3. Likewise, for the 2nd fraction, since 20 × 21 = 420,
    7/20 = 7 × 21/20 × 21 = 147/420
  4. Subtract the two like fractions:
    20/420 - 147/420 = 20 - 147/420 = -127/420

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