Answers

Subtract 20/21 from 63/81

63/81 - 20/21 is -11/63.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 81 and 21 is 567
   
   Next, find the equivalent fraction of both fractional numbers with denominator 567
2. For the 1st fraction, since 81 × 7 = 567,
   63/81 = 63 × 7/81 × 7 = 441/567
3. Likewise, for the 2nd fraction, since 21 × 27 = 567,
   20/21 = 20 × 27/21 × 27 = 540/567
4. Subtract the two like fractions:
   441/567 - 540/567 = 441 - 540/567 = -99/567
5. After reducing the fraction, the answer is -11/63

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