Answers

Subtract 90/9 from 72/21

1^st number: 3 9/21, 2^nd number: 10 0/9

72/21 - 90/9 is -46/7.

Steps for subtracting fractions

1. Find the least common denominator or LCM of the two denominators:
   LCM of 21 and 9 is 63
   
   Next, find the equivalent fraction of both fractional numbers with denominator 63
2. For the 1st fraction, since 21 × 3 = 63,
   72/21 = 72 × 3/21 × 3 = 216/63
3. Likewise, for the 2nd fraction, since 9 × 7 = 63,
   90/9 = 90 × 7/9 × 7 = 630/63
4. Subtract the two like fractions:
   216/63 - 630/63 = 216 - 630/63 = -414/63
5. After reducing the fraction, the answer is -46/7

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