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Subtract 21/12 from 30/42

1st number: 30/42, 2nd number: 1 9/12

30/42 - 21/12 is -29/28.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 42 and 12 is 84
  2. For the 1st fraction, since 42 × 2 = 84,
    30/42 = 30 × 2/42 × 2 = 60/84
  3. Likewise, for the 2nd fraction, since 12 × 7 = 84,
    21/12 = 21 × 7/12 × 7 = 147/84
  4. Subtract the two fractions:
    60/84 - 147/84 = 60 - 147/84 = -87/84
  5. After reducing the fraction, the answer is -29/28

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