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Subtract 21/63 from 20/42

20/42 - 21/63 is 1/7.

Steps for subtracting fractions

  1. Find the least common denominator or LCM of the two denominators:
    LCM of 42 and 63 is 126

    Next, find the equivalent fraction of both fractional numbers with denominator 126
  2. For the 1st fraction, since 42 × 3 = 126,
    20/42 = 20 × 3/42 × 3 = 60/126
  3. Likewise, for the 2nd fraction, since 63 × 2 = 126,
    21/63 = 21 × 2/63 × 2 = 42/126
  4. Subtract the two like fractions:
    60/126 - 42/126 = 60 - 42/126 = 18/126
  5. After reducing the fraction, the answer is 1/7

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