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Subtract 21/90 from 9/80

9/80 - 21/90 is -29/240.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 80 and 90 is 720
  2. For the 1st fraction, since 80 × 9 = 720,
    9/80 = 9 × 9/80 × 9 = 81/720
  3. Likewise, for the 2nd fraction, since 90 × 8 = 720,
    21/90 = 21 × 8/90 × 8 = 168/720
  4. Subtract the two fractions:
    81/720 - 168/720 = 81 - 168/720 = -87/720
  5. After reducing the fraction, the answer is -29/240

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