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Subtract 3/40 from 9/21

9/21 - 3/40 is 99/280.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 21 and 40 is 840
  2. For the 1st fraction, since 21 × 40 = 840,
    9/21 = 9 × 40/21 × 40 = 360/840
  3. Likewise, for the 2nd fraction, since 40 × 21 = 840,
    3/40 = 3 × 21/40 × 21 = 63/840
  4. Subtract the two fractions:
    360/840 - 63/840 = 360 - 63/840 = 297/840
  5. After reducing the fraction, the answer is 99/280

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