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Subtract 42/18 from 20/21

1st number: 20/21, 2nd number: 2 6/18

20/21 - 42/18 is -29/21.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 21 and 18 is 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,
    42/18 = 42 × 7/18 × 7 = 294/126
  4. Subtract the two fractions:
    120/126 - 294/126 = 120 - 294/126 = -174/126
  5. After reducing the fraction, the answer is -29/21

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