Answers

Subtract 90/27 from 10/21

1^st number: 10/21, 2^nd number: 3 9/27

10/21 - 90/27 is -20/7.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 27 is 189
   
   Next, find the equivalent fraction of both fractional numbers with denominator 189
2. For the 1st fraction, since 21 × 9 = 189,
   10/21 = 10 × 9/21 × 9 = 90/189
3. Likewise, for the 2nd fraction, since 27 × 7 = 189,
   90/27 = 90 × 7/27 × 7 = 630/189
4. Subtract the two like fractions:
   90/189 - 630/189 = 90 - 630/189 = -540/189
5. After reducing the fraction, the answer is -20/7

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