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Subtract 45/20 from 21/42

1st number: 21/42, 2nd number: 2 5/20

21/42 - 45/20 is -7/4.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 42 and 20 is 420
  2. For the 1st fraction, since 42 × 10 = 420,
    21/42 = 21 × 10/42 × 10 = 210/420
  3. Likewise, for the 2nd fraction, since 20 × 21 = 420,
    45/20 = 45 × 21/20 × 21 = 945/420
  4. Subtract the two fractions:
    210/420 - 945/420 = 210 - 945/420 = -735/420
  5. After reducing the fraction, the answer is -7/4

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