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Subtract 21/12 from 30/90

1st number: 30/90, 2nd number: 1 9/12

30/90 - 21/12 is -17/12.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 90 and 12 is 180
  2. For the 1st fraction, since 90 × 2 = 180,
    30/90 = 30 × 2/90 × 2 = 60/180
  3. Likewise, for the 2nd fraction, since 12 × 15 = 180,
    21/12 = 21 × 15/12 × 15 = 315/180
  4. Subtract the two fractions:
    60/180 - 315/180 = 60 - 315/180 = -255/180
  5. After reducing the fraction, the answer is -17/12

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